1000 words and three scholarly references

https___dftj9wb4gc6c5.cloudfront.net_Bethel_Courses_HEA_2010_Unit_3_read1.pdf

Home >Law homework help >1000 words and three scholarly references

199

Flexibility

LEARNING OBJECTIVES

After completing the study of this concept, you will be able to:

▶ Identify and explain several misconceptions about flexibility. ▶ List the health benefits of flexibility and stretching. ▶ Describe the various methods of stretching and their advantages and disadvantages.

▶ Determine the amount of exercise necessary to improve flexibility, explain the FIT formulas for the different types of stretching, and describe factors in the “do and don’t list for stretching.”

▶ Describe a variety of flexibility-based activities for improving flexibility and some of the advantages and disadvantages of each.

▶ Identify some of the guidelines for safe and effective stretching.

▶ Describe several self- assessments for flexibility, select the self-assessments that help you identify personal needs, and plan (and self-monitor) a personal flexibility exercise program.

C o

n c

e p

t 1 0

• Regular stretching exercises promote flexibility,

a component of fitness that permits freedom of

movement, contributes to ease and economy of

muscular effort, allows for successful performance in

certain activities, and provides less susceptibility to

some types of injuries or musculoskeletal problems.

cor22568_ch10_199-224.indd 199 17/08/12 9:24 PM

F O S T E R , C E D R I C 1 6 9 2 T S

200 Section 3 ▶ The Physical Activity Pyramid

is described by the arc through which a joint moves and is typically measured in degrees using a tool called a goni- ometer. The direction of movement at a specific joint is determined by the shapes of the bony surfaces that are in contact. Certain types of joints allow for greater move- ment than others. In fact, flexibility is highly joint spe- cific. An individual may demonstrate optimal flexibility in one region of the body but not in others. For example, a person may have good flexibility of the spine, hips, and legs in order to reach down and touch the toes, but is unable to clasp both hands behind the back due to stiff- ness of the shoulder joints.

Medical professionals use a specific vocabulary to describe the movement of joints. Figure 1 illustrates some of these movement terms as they relate to hip, knee, or ankle motion. Similar terms are applied in describing movement of the spine and upper body. Note that the same terms (such as flexion/extension ) can be applied to dif- ferent joints, while other terms (such as dorsiflexion/plantar flexion ) are unique to a specific joint such as the ankle.

The shape, size, and orientation of a joint greatly

influence the amount of motion available. The circular surface of the ball-and-socket joint of the hip, for example, allows for considerable mobility, includ- ing movement to the side (adduction and abduction), forward and backward (flexion and extension), and in

F lexibility refers to the amount of motion that is possible at a given joint or series of joints. A joint with

limited ability to bend or straighten is said to be tight or stiff, while joints with a high degree of flexibility are loose-jointed, or hypermobile. A reasonable amount of flexibility is needed to perform efficiently and effectively in daily life, but excessive flexibility is not desirable.

Flexibility is important for good health because it helps with the maintenance of good posture and the prevention of back and neck problems. It directly con- tributes to wellness as it enables people to move more freely and perform daily tasks more effectively, which is especially important for maintaining independence and function later in life. Lastly, flexibility contributes to improved performance in sports. Good flexibility is obvi- ous in sports such as gymnastics, figure skating, diving, wrestling, and swimming, but it contributes to dynamic movement and performance in many other sports as well.

While these points are widely accepted, there are a number of misconceptions about flexibility, stemming largely from confusion about differences between flex- ibility and stretching. Flexibility is a state of being and something that can be measured. Stretching, in contrast, is a behavior that can improve flexibility if performed regu- larly. The effects of stretching and of flexibility must be considered independently to interpret research in this area. For example, research has shown that stretching may have little impact on injuries during a bout of physi- cal activity, but this does not discount the benefits of good flexibility (and broader indicators of functional fitness) on injury prevention. Similarly, research now indicates that stretching prior to exercise may (in some circumstances) reduce performance in some speed and power activities. This has caused some athletes to erroneously assume that stretching (and flexibility) is not important and even det- rimental to their performance. Stretching should still be an important part of a training program for athletes, but, as described later in this concept, the timing and length of stretches are critical for optimal results.

This concept will further clarify the distinctions between flexibility and stretching. The initial sections explain the factors influencing flexibility and how flexibility impacts health and wellness. We look at various stretching methods for improving flexibility and the recommended amounts to perform. The final section covers flexibility-based activities and guidelines for incorporating stretching into your fit- ness program.

Flexibility Fundamentals The range of motion in a joint or joints is a reflection

of the flexibility at that joint. Clinically, the range of motion (ROM) of a joint is the extent and direction of movement that is possible. The extent of movement

Adduction

Flexion

Abduction Extension

Extension

Flexion

Dorsiflexion

Plantar flexion Eversion

Inversion

Hip

Knee

Ankle

Figure 1 ▶ Ranges of joint motion.

cor22568_ch10_199-224.indd 200 17/08/12 9:25 PM

F O S T E R , C E D R I C 1 6 9 2 T S

Concept 10 ▶ Flexibility 201

and out (internal and external rotation). The hinge joint of the knee is more restrictive and limits movement to primarily forward and backward (flexion and extension). Motion at other joints, such as the ankle, involves the combined movements of numerous bony surfaces. A hinge-type portion permits the up and down motion of the foot (dorsiflexion and plan- tar flexion), while a separate planar-type joint allows the side-to-side motion (inversion and eversion) of the foot. A basic understanding of this terminology is important in understanding principles of flexibility and stretching.

Flexibility is influenced by the extensibility of soft

tissues such as muscles, tendons, and ligaments.

Soft tissues are made up of a number of substances, including fibers called collagen and elastin. These struc- tural building blocks influence the degree of extensibility of tissues such as ligaments , tendons , and muscles. Tis- sues with a greater proportion of collagen fibers tend to be stiffer while those with more elastin tend to bend and stretch more readily. Ligaments contain a greater pro- portion of collagen and this enhances their function in providing rigidity and stability to a joint and their role in restricting excessive joint motion. Damage to ligaments from repeated sprains can lead to excessive joint laxity and increased risk for injuries. Tendons contain a greater proportion of elastin than ligaments but muscles contain even more and this contributes to their relatively high degree of flexibility. Together, the muscles and tendons are referred to as a muscle-tendon unit (MTU) and due to their connection, they are both stretched together. In this book we will generally refer to muscles or tissues rather than the MTU.

The short-term gains in range of motion immediately following stretching are commonly attributed to changes in the “viscoelastic” properties of muscle. Viscosity refers to a property that allows tissues to undergo slow changes in length over time (like taffy) while elasticity refers to a property that allows tissues to return to normal shape after being stretched (like a rubber band). When a muscle is stretched, there are changes in muscle length as well as a decline in muscle stiffness . However, due to the elas- tic nature of the MTU, these changes are short-lived. In fact, studies have shown that the beneficial effects of a 30- or 45-second static stretch can disappear in less than 30 seconds. Thus, changes in viscoelasticity contribute to small temporary changes in muscle length and stiffness rather than long-term changes in flexibility.

Some regions of the body are more prone to

tightness than others. A number of muscles in the body have a predictable tendency toward tightness. Cli- nicians refer to these muscles as “tonic” or “postural” muscles because of their tendency to tighten or shorten.

A characteristic of these muscles is that they tend to cross more than one joint. Included in the list are the upper trapezius, the muscles at the base of the skull, the pecto- ralis, hip flexors, low back extensors, hamstrings, adduc- tors, and calf muscles. These muscles typically benefit the most from stretching and therefore are often targeted by common stretching exercises. Specific exercises for these muscle groups are provided at the end of the concept.

Static flexibility is different from dynamic flexibility.

A joint’s flexibility can be described differently depending on how it is assessed. Static flexibility is the maximum range a joint can achieve under stationary conditions. An example is the hip ROM achieved during a hamstring stretch. Static flexibility is limited by passive viscous and elastic properties of the muscles. Dynamic flex- ibility is the maximum range a joint can achieve under active conditions. An example is the maximum height and position of a hurdler’s lead leg. While it may seem logi- cal that dynamic flexibility would be greater than static, the opposite is true. This is because dynamic flexibility is influenced by both passive and dynamic properties of the tissues. A hurdler’s performance, for example, depends on the passive muscle and tendon extensibility as well as the ability to move against gravity, at fast speeds, and without elicitation of a stretch reflex. While good static flexibil- ity is necessary for good dynamic flexibility, it does not ensure it. Athletes must train both static and dynamic flexibility for optimal performance.

Factors Influencing Flexibility Flexibility varies considerably across the lifespan. Flexibility is generally high in children but declines during adolescence because of the rapid changes in

Range of Motion (ROM) The full motion possible in a joint or series of joints. Ligaments Bands of tissue that connect bones. Unlike muscles and tendons, overstretching liga- ments is not desirable. Tendons Fibrous bands of tissue that connect mus- cles to bones and facilitate movement of a joint. Laxity Motion in a joint outside the normal plane for that joint, due to loose ligaments. Muscle-Tendon Unit (MTU) The skeletal muscles and the tendons that connect them to bones. Stretch- ing to improve flexibility is associated with increased length of the MTU. Stiffness Elasticity in the MTU; measured by force needed to stretch.

VIDEO 1

cor22568_ch10_199-224.indd 201 17/08/12 9:25 PM

F O S T E R , C E D R I C 1 6 9 2 T S

202 Section 3 ▶ The Physical Activity Pyramid

growth—essentially, the bones grow faster than the soft tissues. In early adulthood, the muscles and tendons catch up to the skeletal system, causing flexibility to peak in the mid- to late 20s. With increasing age, range of motion tends to decline again. Reduced flexibility is due to a loss of elasticity in the MTU and cross-linkages within col- lagen fibers of the tendons, ligaments, and joint capsules. Over the span of their working lives, adults typically lose 3 to 4 inches of lower back flexibility as measured by the common “sit-and-reach” test. Research studies have confirmed that declines in flexibility are not as evident in individuals who maintain regular patterns of physical activity. The use of planned stretching programs has also been shown to help maintain flexibility with age.

Gender differences exist in flexibility. Girls tend to be more flexible than boys at young ages, but the gen- der difference decreases for adults. Greater flexibility of females is generally attributed to anatomical differences (e.g., wider hips) and hormonal influences.

Genetic factors can explain some individual variability

in flexibility. In some families, the trait for loose joints is passed from generation to generation. This hy permobility is sometimes referred to as joint looseness. Studies show that people with this trait may be more prone to joint disloca- tion. There is not much research evidence, but some experts believe that those with hypermobility may also be more sus- ceptible to athletic or dance injuries, especially to the knee, ankle, and shoulder, and may be more apt to develop prema- ture osteoarthritis.

Lack of use or misuse can cause reductions in

flexibility. Lack of physical activity is one of the major factors contributing to poor flexibility. When muscles are moved as part of normal daily activities or during structured physical activity, the muscles and tendons get stretched. Without this regular stimulation, flexibility will decrease.

Improper exercise can lead to muscle imbalances that may negatively impact flexibility. The most common example is when body builders overdevelop their biceps in comparison to their triceps. This leads to a muscle- bound look characterized by a restricted range of motion in the elbow joint. To avoid this, it is important to exer- cise muscles through the full range of motion.

Health Benefits of Flexibility and Stretching Adequate flexibility is necessary for achieving and

maintaining optimal posture and movement patterns.

Good posture implies that the body’s segments are well- aligned for efficient function and the least amount of strain. Poor posture, on the other hand, places body seg- ments at a biomechanical disadvantage, adding stress and strain to the body with eventual wear and tear on the joints and tendons. In many cases, poor posture occurs over time due to poor habits. Sensory receptors in the skin and joints appear to maintain poor posture through feedback loops within the nervous system. The nervous system keeps some muscles overly active and “tight” and others overly quiet or “weak.” This feedback loop rein- forces the muscle imbalance and the poor posture—long/ weak muscles on one side of the body are countered by muscles on the opposite side of the body which are too short/tight. Postural correction begins by improving the flexibility of the shortened muscles, followed by strength- ening of the “weak” muscles, and finally use of improved body awareness.

Good flexibility and posture are also important for optimal movement patterns of the limbs and trunk. When good flexibility and posture are sacrificed, move- ment patterns can be adversely affected, resulting in joint motion that is either too restricted or too excessive. Poor movement patterns add stress and strain to adjoin- ing joint structures, leading to possible damage of the joints or tendons. For example, motion of the shoulder is adversely affected by a slouched posture. The arm can be raised further over the head from an upright posture than a slouched posture. To develop and maintain good posture and movement patterns, muscles must have suf- ficient flexibility and appropriate levels of strength. Addi- tional information on posture and back care is presented in Concept 11.

T E C H N O L O G Y U P D A T E

Software Facilitates Stretching at Work Millions of people have sedentary office jobs that require them to be at their desk all day, which isn’t good for your body. New computer software may help address this prob- lem. One commercially available program generates a series of pop-up reminders that prompt you to periodically move or take stretching breaks during the day. The user can con- trol the frequency of the prompts; but if you skip the rec- ommended prompt, an animated avatar delivers a stronger message encouraging you to take a break. The theory behind these tools is that the periodic prompts and remind- ers will help encourage workers to take brief stretch breaks to break up computer/sedentary time and reduce risk of repetitive motion injuries and fatigue,.

What impact would this type of tool have on your daily activity

pattern?

ACTIVITY

cor22568_ch10_199-224.indd 202 17/08/12 9:25 PM

F O S T E R , C E D R I C 1 6 9 2 T S

Concept 10 ▶ Flexibility 203

Flexibility contributes to functional fitness, which

has been shown to provide protection against risks

for injury. Many people stretch before exercise because they believe it is important for reducing the likelihood of getting injured. A good warm-up probably helps to prepare the body for exercise, but the consensus in the literature is that stretching does not reduce the risks for musculotendinous injuries. However, this may be an oversimplification. A recent study showed considerable individual variability in effects. People that currently stretched were at greater risk of injury if they stopped stretching. People that never stretched were at greater risk of injury if they started stretching. (See In the News for details on this study).

While stretching may not directly impact risk of injury, research is accumulating on the importance of flexibility for overall injury prevention. In this recent work, flexibility is a key contributor to a broader con- struct of functional fitness which also incorporates core strength, balance, and agility. Several different functional movement batteries have been developed to identify indi- viduals that may have poor levels of functional fitness. The screening assessments typically score individuals based upon the quality of motion during basic func- tional movement tasks, each requiring a combination of strength, balance, dynamic, and/or static flexibility. The screening movements are used to identify asymmetries and functional limitations that may predispose people to injury. Studies have shown the utility of these tests for predicting risks of injuries in football players, firefight- ers, and military personnel. They have not been widely used for preventive health screens, but this will likely follow. Detailed information about functional fitness would allow clinicians and health and fitness profession- als to design effective interventions and track progress over time.

Stretching is used to assist in rehabilitation from

injuries and for prevention. Physical therapists and athletic trainers frequently prescribe stretching to help patients regain normal range of motion or function or to reduce pain after injury. Typical injuries include muscle strains, ligamentous sprains, and open wounds. Joint stiff- ness is also a common problem following surgery to the shoulder, knee, and ankle or following immobilization of any fracture in a cast or walking boot. In each case, gentle stretching and range of motion exercises are used to stimulate the healing process and add strength to the healing tissues. Prior to stretching, tissues are warmed up through the use of active exercise, massage techniques, or modalities such as moist heat or ultrasound. Stretch- ing is followed by exercises to increase strength within

Changing Your Stretching Routine May Impact Your Injury Risk You may think that stretching prior to exer- cise reduces the risk of injury, but research

doesn’t necessarily support this. A recent study followed more than 2,000 runners to examine the impact of stretch- ing on injury. Participants were assigned to one of four groups: those who continued with their normal pre-run rou- tine (maintaining an existing pattern of either stretching or nonstretching) and those who altered their normal pre-run routine (adding or deleting stretching to the existing routine). Interestingly, the groups that were asked to alter their normal

pre-run routines (performing or not performing stretching) demonstrated an increased risk of injury by 40 percent. Those that continued their normal pre-run routine (whatever it was) had no increased risk for injury. This suggests that people may accommodate to stretching and that need for (and response to) pre-exercise stretching may vary across individuals.

Does this finding change your opinion of whether you should stretch

prior to exercise? Why or why not?

CC Y c

ACTIVITY

In the News

Health is available to Everyone for a

Lifetime, and it’s Personal

The concept of functional fitness has generated consid- erable interest among health and fitness professionals. Many fitness centers offer group classes focused on improving functional fitness and these courses typically involve flexibility and functional movement tasks.

Do you believe that flexibility and functional fitness provide

important benefits to your health now or do you think the

benefits may be more relevant as you age? How does this

influence your current views about stretching and flexibility

exercise?

ACTIVITY

Hypermobility Looseness or slackness in the joint and of the muscles and ligaments (soft tissue) sur- rounding the joint.

cor22568_ch10_199-224.indd 203 17/08/12 9:25 PM

F O S T E R , C E D R I C 1 6 9 2 T S

204 Section 3 ▶ The Physical Activity Pyramid

the newly-gained range of motion and neuromuscular activities to restore functional movement patterns. Physi- cal therapists and athletic trainers prescribe stretching to assist in rehabilitation and recovery, but it is up to the patient to perform the recommended stretching exercises.

Stretching may contribute to treatment of

musculoskeletal pain. Stretching is often one compo- nent of a larger treatment plan for addressing low back and neck pain, muscle strains, and joint stiffness post surgery or following immobilization. Because it is rarely used as the sole treatment approach, it is difficult to isolate its effec- tiveness from other treatments commonly provided. How- ever, it has been shown to be as effective as strengthening or massage in the treatment of chronic neck pain. Additionally, movement-based activities such as tai chi have been shown to facilitate movement and reduce low back pain.

Stretching may help relieve muscle cramps and

pain associated with myofascial trigger points.

Many people experience some form of muscle cramp- ing during exercise. A muscle spasm or cramp may result for various reasons, including overexertion, dehydration, and heat stress. Stretching a cramped (but not a strained) muscle will often help relieve the cramp. We have less understanding of myofascial trigger points, but they are typically more painful than cramps. They are char- acterized by taut bands within skeletal muscle that have a nodular texture. They are sensitive to touch and can produce a radiating pain in specific regions of the body when touched. Trigger points can be caused by trauma, or occur after overuse or from prolonged spasm in the

muscles. The application of direct pressure on myofascial trigger points followed by stretching has been shown to help relieve pain. However, stretching has less effect on relieving nonspecific areas of soft tissue tenderness in the body (often referred to as tender points).

Stretching is probably ineffective in preventing

muscle soreness. In the past, it was suggested that stretching during a cool-down will prevent muscular sore- ness. In a controlled study, however, muscle soreness was deliberately induced in a group of subjects. When half of the group stretched immediately afterward and at inter- vals for 48 hours, they had as much soreness as the group who did not stretch. While studies have shown limited effects of stretching on reducing soreness, it is still a useful part of an overall cool-down routine following exercise.

Good flexibility can be beneficial to one’s ability to

function effectively at work and in daily life. Lack of joint range of motion can negatively affect one’s ability to perform tasks at work and daily activities such as driving a car. It is well documented that as people grow older their range of motion in the neck decreases resulting in reduced ability to turn the head and effectively anticipate move- ments to the side and rear of the car. Reduced range of motion can also increase risk of accidents in automobiles and around the home. Regular stretching is important to everyday functioning in a variety of settings.

Stretching Methods Static stretching is the safest and most commonly

used method of stretching. Static stretching is done slowly and held for a period of several seconds. The probability of tearing the soft tissue is low if performed properly. Static stretches can be performed with active assistance or with passive assistance . When active

Physical therapists and athletic trainers use carefully planned stretching exercise for treatment.

Trigger Points Especially irritable spots, usually tight bands or knots in a muscle or fascia (a sheath of connective tissue that binds muscles and other tissues together). Trigger points often refer pain to another area of the body. Active Assistance An assist to stretch from an active contraction of the opposing (antagonist) muscle. Passive Assistance Stretch imposed on a muscle with the assistance of a force other than the opposing muscle.

VIDEO 2

cor22568_ch10_199-224.indd 204 17/08/12 9:25 PM

F O S T E R , C E D R I C 1 6 9 2 T S

Concept 10 ▶ Flexibility 205

Figure 2 ▶ Examples of static, dynamic, and pre-contraction stretches of the calf muscles (gastronemius and soleus). Muscles shown in dark pink are the muscles being contracted. Muscles shown in light pink are those being stretched.

Passive (Self Assisted)

B. Active

Passive (Gravity Assisted)

Passive (Partner Assisted)

E. Active

Passive (Gravity Assisted)

Step 2: Relax calf muscles and contract dorsiflexors (shin muscles) in active stretch of calf. H.

Step 1: From a lengthened position, contract calf muscles isometrically against resistance of rope or partner. G.

Step 3: Continue active contraction while rope provides passive assist.

Contrasting Three Methods of Stretching I. Static Stretch

II. Dynamic Stretch

III. Pre-Contraction Stretch (e.g., PNF Stretch)

cor22568_ch10_199-224.indd 205 17/08/12 9:25 PM

F O S T E R , C E D R I C 1 6 9 2 T S

206 Section 3 ▶ The Physical Activity Pyramid

assistance is used, the opposing muscle group is contracted to produce a reflex relaxation (reciprocal inhibition) in the muscle being stretched. This enables the muscle to be more easily stretched. For example, when doing a calf stretch exercise (see Figure 2A, page 205), the muscles on the front of the shin are contracted to assist in the stretch of the muscles of the calf. However, active assistance to static stretching has one problem. It is almost impossible to produce adequate overload by simply contracting the opposing muscles.

When passive assistance (see Figure 2B , C ) is used, an outside force, such as a partner, aids in the stretching. For example, in the calf stretch, passive assistance can be pro- vided by another person, another body part ( Figure 2B ), or gravity ( Figure 2C ). This type of stretch does not cre- ate the relaxation in the muscle associated with active assisted stretch. An unrelaxed muscle cannot be stretched as far, and injury may happen. Therefore, it is best to combine the active assistance with a passive assistance when performing a static stretch. This gives the advan- tage of a relaxed muscle and a sufficient force to provide an overload to stretch it.

A good way to begin static stretching exercises is to stretch until tension is first felt, back off slightly and hold the position several seconds, and then gradually stretch a little farther, back off, and hold. Decrease the stretch slowly after the hold.

Dynamic stretching can be safe and effective if

performed properly. Dynamic stretching uses gradual and controlled movement of body parts up to the limit of a joint’s range of motion. Stretches may involve arm or leg swings of increasing reach or increasing speed. The key is to perform the movement in a controlled man- ner through the normal range of motion. This approach allows dynamic stretching to be a safe and efficient means

of using active stretching techniques. As with static stretching, the movement can be provided either actively or passively. For example, in the calf stretch shown in Figure 2D , E , and F , the foot is actively bounced for- ward by the antagonist muscle force or passively by an assist from another person or gravity. Dynamic stretching movements are common in many functional fitness pro- grams and hybrid exercise classes.

Ballistic stretching is a specific type of dynamic stretching but it presents risks if not done properly. A ballistic stretch uses momentum to stretch the mus- cles up to (and beyond) their normal range of motion. Momentum is produced by a more vigorous body motion, such as flinging a body part (bobbing) or rock- ing it back and forth to create a bouncing movement. The inherent problem with most ballistic stretching is lack of control over the force and range of movement. The forceful movement in ballistic stretching may increase risks for injury. Ballistic stretching may be use- ful for some athletes who do sports that involve ballistic movements; however, this form of stretching is not rec- ommended for most people.

Pre-contraction stretching activities such as PNF

have proven to be most effective at improving

flexibility. Proprioceptive neuromuscular facilita- tion (PNF) stretching utilizes techniques to stimulate muscles to contract more strongly (and relax more fully) in order to enhance the effectiveness of stretching. The contract-relax-antagonist-contract (CRAC) technique is the most popular. CRAC PNF involves three specific steps: (1) Move the limb so the muscle to be stretched is elongated initially; then contract it ( agonist muscle ) isometrically for several seconds (against an immovable object or the resistance of a partner); (2) relax the muscle; and (3) immediately stati- cally stretch the muscle with the active assistance of the antagonist muscle and an assist from a partner, gravity, or another body part. Figure 2G , H , and I provide a detailed illustration of how this technique is applied to the calf stretch. Research shows that this and other types of PNF stretch are more effective than a simple static stretch.

How Much Stretch Is Enough? The appropriate amount of flexibility for health is

not known. Flexibility is joint specific, so the amount of flexibility varies by joint. Norms are available for the amount of flexibility for males and females of different ages, but it is not clear how much is needed for health. For example, there is little scientific evidence to indicate that a person who can reach 2 inches past his or her toes on a sit-and-reach test is less fit (or healthy) than a person who

VIDEO 3

Dynamic flexibility is important in many sports.

cor22568_ch10_199-224.indd 206 17/08/12 9:25 PM

F O S T E R , C E D R I C 1 6 9 2 T S

Concept 10 ▶ Flexibility 207

can reach 8 inches past the toes. The standards presented in the Lab Resource Materials are based on the best avail- able evidence.

Too much flexibility (hyperflexibility) in a joint may

increase susceptibility to injury. While an appropri- ate amount of flexibility is beneficial, too much flexibil- ity can compromise the integrity of the joint and make it less stable and prone to injury. Most muscles and tendons can lengthen (extensibility) and return to their normal length after appropriate stretching (elasticity). However, short, tight muscles and tendons can be easily overstretched (strained). Even more likely to be injured are the ligaments that connect bone to bone. Liga- ments and the joint capsule lack the elasticity and tensile strength of the muscles and tendons. When involun- tarily overstretched, they may remain in a lengthened state or become ruptured (sprained). If this occurs, the joint loses stability and is susceptible to chronic disloca- tion, repeated sprains, and excessive wear and tear of the joint surface. This is particularly true of weight-bearing joints, such as the hip, knee, and ankle. Appropriate

stretching techniques can increase flexibility without leading to hyperflexibility.

Specific FIT guidelines are established for safe and

effective stretching. Lifestyle and cardiovascular activ- ity do little to develop flexibility. To build this important part of fitness, stretching exercises from step 5 of the pyramid are essential (see Figure 3 ). The American Col- lege of Sports Medicine (ACSM) recently released new guidelines for effective stretching. The guidelines indi- cate that stretching can be done using static stretches

Avoid Inactivity

Energy Balance

Energy Out (Activity)

Energy In (Diet)

Vigorous Sports and Recreation

Vigorous Aerobics

Moderate Physical Activity

Flexibility Exercises

Muscle Fitness Exercises

• Tennis

• Hike

• Yoga

• Stretch

• Jog

• Bike

• Aerobic dance

• Walk

• Yard work

• Golf

• Calisthenics

• Resistance

exercise

STEP 1

STEP 2

STEP 3

STEP 4

STEP 5

Figure 3 ▶ Flexibility or stretching exercises should be selected from step 5 of the physical activity pyramid. Source: C. B. Corbin

Reciprocal Inhibition Reflex relaxation in stretched muscle during contraction of the antagonist. Ballistic Stretch Bouncing or bobbing to facilitate lengthening of the muscle-tendon unit. Proprioceptive Neuromuscular Facilitation

(PNF) A stretching technique that incorporates muscle contraction prior to stretch.

cor22568_ch10_199-224.indd 207 17/08/12 9:25 PM

F O S T E R , C E D R I C 1 6 9 2 T S

208 Section 3 ▶ The Physical Activity Pyramid

Table 1 ▶ FIT Formula for Stretching—Thresholds and Target Zones

Static Ballistic PNF (CRAC)

Threshold Target Threshold Target Threshold Target

Frequency At least 2 to 3 days a week (threshold)

2–7 days a week At least 2 to 3 days a week (threshold)

2–7 days a week

Intensity Stretch to the point of feeling tightness or slight discomfort. Holding a static stretch for 10–30 seconds is recommended for most adults. In older persons, holding a stretch for 30–60 seconds may give greater benefit.

Add passive assistance.

Avoid overstretching or pain.

Stretch beyond normal length with gentle bounce or swing. Do not exceed 10% of static range of motion.

Same as ballistic threshold

Use a 3- to 6-second contraction at 20%–75% maximum voluntary contraction followed by a 10- to 30-second assisted stretch.

Perform 4–5 reps with 6-second contractions, each followed by a 10–30-second assisted stretch. Thirty seconds between reps.

Time Perform 2 repetitions. Hold each for 15 seconds. Rest 30 seconds between reps.

Perform 3-4 repetitions. Hold each for 15–60 seconds. Rest 30 seconds between reps.

Perform 1 set involving 30 continuous seconds.

Perform 2–3 sets of 30 consecutive seconds of motion. Rest 1 minute between sets.

Perform 2 repetitions. Thirty seconds between reps.

Perform 3-4 repetitions. Rest 30 seconds between reps. Rest 1 minute between sets.

(active or passive), dynamic stretches, or pre-contraction stretches. The recommended threshold and target zones for safe and effective stretching are provided in Table 1 . The threshold of training refers to the minimum amount of stretching required to make gains and/or maintain a level of flexibility. Target zone refers to the overload needed to make significant gains in flexibility or to prog- ress one’s level of flexibility following a plateau.

Stretching should ideally be performed at least

2 to 3 days a week (frequency). The ACSM guide- lines suggest that 2 to 3 days are effective for increasing range of motion, but they point out that gains are greater if performed daily. However, like other forms of exercise, 1 day a week is still better than none. The ACSM guide- lines emphasize that stretching is most effective when the muscles are warm. Performing a light to moderate aerobic warm-up activity prior to stretching can increase internal muscle temperature and the extensibility of soft tissues, allowing for a more effective stretch. Since some people do not want to interrupt their workout in the middle, they prefer to stretch at the end. Stretching at the end of the workout serves a dual purpose—building flexibility and cooling down. It is, however, appropriate to stretch at any time in the workout after the muscles

have been active and are warm. If you prefer to include it at the beginning of a workout, ease into the stretching gradually.

To increase the length of a muscle, stretch it more

than its normal length but do not overstretch it

(intensity). The best evidence suggests that muscles should be stretched to about 10 percent beyond their normal length to bring about an improvement in flexibil- ity. More practical indicators of the intensity of stretch- ing are to stretch just to the point of tension or just before discomfort. Exercises that do not cause an overload will not increase flexibility. Once adequate flexibility has been achieved, range of motion (ROM) exercises that do not require stretch greater than normal can be performed to maintain flexibility and joint range of motion.

To increase flexibility, stretch and hold muscles

beyond normal length for an adequate amount

of time (intensity). When a muscle is stretched (lengthened), the stretch reflex acts to resist the stretch (see Figure 4 ). Sensory receptors (A) in the muscle- tendon unit send a signal to the sensory neurons (B), and these neurons signal the motor neurons (C) to contract (shorten) the muscles (D). This reflex restricts initial

cor22568_ch10_199-224.indd 208 17/08/12 9:25 PM

F O S T E R , C E D R I C 1 6 9 2 T S

Concept 10 ▶ Flexibility 209

efforts at stretching; however, if the stretch is held and maintained over time, the stretch reflex subsides and allows the muscle to lengthen (this phase is called the development phase because this is when improvements occur). Neurological evidence documenting the activa- tion of the stretch reflex during stretching is not avail- able, but the reflex mechanism clearly explains why it is important to hold a stretch for an extended period of time. Attempts to stretch for shorter durations are lim- ited by the opposing action of the opposing muscles (see Figure 4 ). Guidelines suggest that to get the most benefit for the least effort stretches should be held between 10 and 30 seconds. The ACSM suggests that 10 seconds may be an adequate threshold when performing PNF (stretch after muscle contraction).

To increase flexibility, repeat stretching exercises

an adequate number of times (time). Figure 5 shows the typical responses to a stretched muscle during a series of stretches. Tension in a muscle decreases as the stretch is held. Most of the decrease occurs in the first 15 sec- onds. The tension curves are lower with each successive repetition of stretching, which is why multiple sets of stretching are recommended. The ACSM recommends 2–4 reps but, as shown in Figure 5, up to 5 reps can be beneficial.

Principles of overload and progression can be

applied to a regular stretching program to both

improve and maintain flexibility. Threshold of train- ing refers to the minimum amount of stretching required to make gains and/or maintain a level of flexibility. Target zone refers to the overload needed to make significant

gains in flexibility or to progress one’s level of flexibility following a plateau. There are no accepted guidelines for scientifically progressing stretching exercises, but the principles of overload and specificity described for mus- cle fitness would apply. Principles of threshold and target zones are presented in Table 1 for each type of stretching.

Regular stretching exercise (based on the FIT

guidelines) leads to improved range of motion,

but the mechanisms of action are not completely

understood. As previously described, the increases in muscle length and reductions in stiffness immediately following stretching are temporary. However, regular stretching does lead to improvements in flexibility. Many scientists believe that the resulting gains in motion fol- lowing stretching are due as much to sensory changes in the nervous system as to increased muscle length or reduced muscle stiffness. According to the theory, stretch- ing leads to increases in stretch tolerance which causes people to perceive discomfort at greater ranges of motion.

Spinal cord

Motor neuron

(C)

Sensory receptor

Direction of impulse

Sensory neuron (B)

Patella

Receptor—ends of (A) sensory neuron

Effector quadriceps femoris muscle group

(D)

Figure 4 ▶ The stretch reflex. Source: Shier, Butler, and Lewis.

M u

sc le

t en

si o

n Time in seconds

Stretch 1

Stretch 2

Stretch 3

Stretch 4

Stretch 5

20 30 40 50 60

Figure 5 ▶ Typical responses to a stretched muscle during a series of stretches.

Range of Motion (ROM) Exercises Exercises used to maintain existing joint mobility (to prevent loss of ROM). Stretch Tolerance Greater stretch for the same pain level.

cor22568_ch10_199-224.indd 209 10/09/12 7:00 PM

F O S T E R , C E D R I C 1 6 9 2 T S

210 Section 3 ▶ The Physical Activity Pyramid

For example, an individual that regularly performs stretches for tight hamstring muscles may see improve- ments in range of motion during a straight leg raise. The sensory theory explains that much of the improvement in range of motion is due to a change in sensation. In other words, the perceived onset of pain is now further toward the end range of motion. The sensory theory has also been used to explain individual differences in flexibility. Persons that are hypermobile or very flexible may not have longer muscles or looser joints but rather perceive the physical limits later in the arc of motion.

Flexibility-Based Activities The popularity of flexibility-based activity has

increased in recent years. A recent survey of World- wide Fitness Trends indicates that of the 20 top trends, 6 relate to flexibility. Included are yoga, functional fitness training, special training for older adults, core training, Pilates, and sport-specific training. Data from the Sport- ing Goods Manufacturers Association (SGMA) also indi- cates that yoga and tai chi are among the fastest growing activities. The popularity of these activities suggests that people may be more interested in flexibility-related activity when it is presented in an engaging and interac- tive format. Some of the growth may also be attributed to increased acceptance of these activities by medical professionals. Distinctions between these activities are provided below.

Tai chi is one of the safest and more established

movement disciplines. Tai chi (often translated as Chinese shadow boxing) is considered a martial art but involves the execution of slow, flowing movements called “forms.” Numerous studies have supported the benefits of tai chi on a variety of health-related parameters, includ- ing flexibility, muscular strength, balance, posture, pain relief, stress, weight reduction, and cardiovascular fitness. Recent studies have shown that tai chi can be particularly useful for people with arthritis, strengthening muscles by using both isometric (holding) and isotonic (mov- ing) muscle contractions. Studies have shown strength gains of 15 to 20 percent in elderly tai chi participants. This improved strength translates into joint protection and stability, as well as increased strength for daily liv- ing tasks. The highly cited FICSIT study demonstrated significant benefits of tai chi on balance and risk of falls in the elderly. Young participants can benefit as well.

Yoga is a diverse and controversial movement

discipline. Yoga is an umbrella term that refers to a number of yoga traditions. The foundation for most

yoga traditions is hatha yoga, which incorporates a variety of asanas (postures). Iyengar yoga is another popular variation. It uses similar asanas as hatha yoga but uses props and cushions to enhance the move- ments. Emphasis is placed on balance through coor- dinated breathing and precise body alignment. Most forms of yoga are considered to be safe, but positions in some of the extreme yoga disciplines have been crit- icized by movement specialists and physical therapists as causing more harm than good, so care should be used when performing some movements. Evidence for health benefits of yoga are not as established as those for tai chi.

Pilates classes are a popular offering at many

fitness centers and health clubs. Pilates is a thera- peutic exercise regimen that combines strength and flex- ibility movements. It was originally developed as more of a therapeutic form of exercise, but it is increasingly being promoted as an overall form of conditioning. Emphasis in Pilates exercise is on core stabilization movements and enhanced body awareness, but classes typically include some stretching activities as well.

Yoga and other movement classes involving stretching are increasingly popular.

cor22568_ch10_199-224.indd 210 17/08/12 9:25 PM

F O S T E R , C E D R I C 1 6 9 2 T S

Concept 10 ▶ Flexibility 211

Check the qualifications of instructors conducting

flexibility-related classes. The popularity of flexibil- ity exercise has led to an increasing array of classes, vid- eos, and resources available for tai chi, yoga, and Pilates. When reviewing these programs and materials, keep in mind that presently there is not a strong scientific basis for yoga and Pilates programming. When per- formed safely with a qualified instructor, they probably can be beneficial. However, many of the positions and movements may be contraindicated exercises that could increase risk for injuries. If you choose to participate in these activities, seek qualified instructors and progress gradually. See Concept 11 for more information about safe and contraindicated exercises.

Guidelines for Safe and Effective Stretching Exercise There is a correct way to perform flexibility

exercises. Remember that stretching can cause muscle soreness, so “easy does it.” Start at your threshold if you are unaccustomed to stretching a given muscle group; then increase within the target zone. The list in Table 2 will help you gain the most benefit from your exercises.

Stretching is specific to each muscle or muscle

group. No single exercise can produce total flexibility. For example, stretching tight hamstrings can increase the

A CLOSER LOOK

Potent Health Benefits from Tai Chi Tai chi can improve flexibility, improve balance, improve lower leg strength, improve immune capacity, build bone density, reduce fall risk, improve cardiovascular func- tion, reduce stress, and improve quality of life. The evi- dence for most health outcomes has been substantiated in well-controlled clinical trials. Interestingly, scientists really don’t have a good sense of how tai chi works to improve these outcomes. The movements are very slow and controlled, so it is likely that the effects are related in part to the concentration and focus required to exe- cute the various movements rather than the movements themselves.

In what ways could you benefit from tai chi?

Potent H

BeHealtht Health

ACTIVITY

T able 2 ▶ Do and Don’t List for Stretching

Do Don’t

Do warm muscles before you attempt to stretch them. Don’t stretch to the point of pain. Remember, you want to stretch muscles, not joints.

Do stretch with care if you have osteoporosis or arthritis. Don’t use ballistic stretches if you have osteoporosis or arthritis.

Do use static or PNF stretching rather than ballistic stretching if you are a beginner.

Don’t perform ballistic stretches with passive assistance unless you are under the supervision of an expert.

Do stretch weak or recently injured muscles with care. Don’t ballistically stretch weak or recently injured muscles.

Do use great care in applying passive assistance to a partner; go slowly and ask for feedback.

Don’t overstretch a muscle after it has been immobilized (such as in a sling or cast) for a long period.

Do perform stretching exercises for each muscle group and at each joint where flexibility is desired.

Don’t bounce muscles through excessive range of motion. Begin ballistic stretching with gentle movements and gradually increase intensity.

Do make certain the body is in good alignment when stretching. Don’t stretch swollen joints without professional supervision.

Do stretch muscles of small joints in the extremities first; then progress toward the trunk with muscles of larger joints.

Don’t stretch several muscles at one time until you have stretched individual muscles. For example, stretch muscles at the ankle, then the knee, then the ankle and knee simultaneously.

length of these muscles but will not lengthen the muscles in other areas of the body. For total flexibility, it is impor- tant to stretch each of the major muscle groups and to use the major joints of the body through full range of normal motion.

cor22568_ch10_199-224.indd 211 17/08/12 9:25 PM

F O S T E R , C E D R I C 1 6 9 2 T S

212 Section 3 ▶ The Physical Activity Pyramid

A flexibility workout should be done when the body

is warmed up and when adequate time is available

to perform stretching exercises . As noted in Concept 3, stretching can be done as one part of a comprehensive warm-up routine. While a warm-up may have benefits, stretching before exercise is not a substitute for a regular stretching program to build flexibility. If you are not flexible and have short muscles, a single warm-up cannot make you flexible. Regular stretching is needed to see improvements in flexibility.

The consensus is that stretching exercise is most effective when the body is already warmed up. For this reason, some people prefer to perform their stretch- ing routine at the end of a workout when muscles are warm. Others prefer to perform their flexibility work- out at a time when they can concentrate specifically on building flexibility. In either case, sufficient time should be allowed to ensure that the exercises are done correctly.

Specialized equipment may help improve the

effectiveness and ease of stretching exercise. One advance in equipment technology for flexibility training is the development of “stretching ropes.” These ropes have multiple loops, which enable individuals to change the length of the rope and perform a variety of different exercises. This feature provides an easy way to put mus- cles on stretch and to vary the degree of stretch. Because you can apply resistance through the elastic straps, it is even possible to perform PNF stretching without the assistance of a partner. A variety of stretching ropes are available on the market, and they all provide similar functionality.

To get the most out of yoga, tai chi, and Pilates classes, find a qualified instructor.

Strategies for Action

An important step for developing and

maintaining flexibility is assessing

your current status. There are dozens of tests of flexibility. Four tests that assess range of motion in the major joints of the body, that require little equipment, and that can be easily administered are presented in the Lab Resources Materials at the end of this concept. In Lab 10A , you will get an opportu- nity to try these self-assessments. Perform these assessments before you begin your regular stretching program and use these assessments to reevaluate your flexibility periodically.

Scores on flexibility tests may be influenced by several

factors. Your range of motion at any one time may be influenced by your motivation to exert maximum effort, warm-up preparation, muscular soreness, tolerance for pain, room temperature, and ability to relax. Recent stud- ies have found a relationship between leg or trunk length and the scores made on the sit-and-reach test. The sit-and- reach test used in this book is adapted to allow for differ- ences in body build.

VIDEO 4

cor22568_ch10_199-224.indd 212 17/08/12 9:25 PM

F O S T E R , C E D R I C 1 6 9 2 T S

Concept 10 ▶ Flexibility 213

Web Resources Functional Movement.com (functional fitness information)

www.Functionalmovement.com Gray Institute (information on functional fitness) www

. Grayinstitute.com National Center for Complementary and Alternative Medicine

http://nccam.nih.gov/

Suggested Readings ACSM. 2010. ACSM’s Guidelines for Exercise Testing and

Prescription. 8th ed. Philadelphia: Lippincott, Williams & Wilkins, Chapter 7.

Kay, A. D., and A. Blazevich. J. 2011. Effect of acute static stretch on maximal muscle performance: A systematic review. Medicine and Science in Sports and Exercise. Available at www.ncbi.nlm.nih.gov/pubmed/21659901

Kiesel, K., P. Plisky, and M. Voight. 2007. Can serious injury in professional football be predicted by a preseason functional movement screen? North American Journal of Sports and Physical Therapy 2(3):147–150.

Kovacs, M. 2009. Dynamic Stretching: The Revolutionary New Warm-up Method to Improve Power, Performance and Range of

Motion. Berkeley, CA: Ulysses Press. McAttee, R., and J. Charland. 2011. Facilitated Stretching. 4th ed.

Champaign, IL: Human Kinetics. (iPad version with video) O’Connor, F. G., et al. 2011. Functional Movement Screen-

ing: Predicting Injuries in Officer Candidates. Medicine and Science in Sports and Exercise 43(12):2224–2230.

Page, P. 2012. Current concepts in muscle stretching for exer- cise and rehabilitation. The International Journal of Sports Physical Therapy 7(1):109–118.

Pereles, D., A. Roth, and D. J. S. Thompson. 2010. A large, rando- mized, prospective study of the impact of a pre-run stretch on the risk of injury in teenage and older runners. USA Track and Field. http://www.usatf.org/stretchStudy/StretchStudyReport.pdf

Thompson, W. R. (2011). Worldwide survey of fitness trends for 2012. ACSM’s Health and Fitness Journal 15(6):9–18.

Weppler, C. H., and S. P. Magnusson. 2010. Increasing muscle extensibility: A matter of increasing length or modifying sensation? Physical Therapy 90(3):438–450.

Yeh, G. Y., et al. 2011. Tai chi exercise in patients with chronic heart failure: A randomized clinical trial. Archives of Internal Medicine 171(8):750–757.

Select exercises that promote flexibility in all areas of the

body. For total body flexibility, 8 to 10 stretching exercises for the major muscle groups of the body are recommended. Table 3 describes some of the most effective exercises for a basic flexibility routine. Individual stretching needs may vary, but the most common areas to target are the trunk, the legs, and the arms. A variety of stretches for these areas are described in Tables 3 , 4 , and 5 . Most are designed for static

stretching, but the pectoral stretch and back-saver hamstring stretch use PNF techniques. Ballistic stretching exercises are discussed in more detail in Concept 12 .

Keeping records of progress will help you adhere to a

stretching program. An activity logging sheet is provided in Lab 10B to help you keep records of your progress as you regularly perform stretching exercises to build and maintain good flexibility.

ACTIVITY

Healthy People

ACTIVITY

2020 The objectives listed below are societal goals designed to help all Americans improve their health between now and the year 2020. They were selected because they relate to the con- tent of this concept.

• Increase proportion of people who regularly perform exer- cises for flexibility.

• Reduce sports and recreation injuries.

• Reduce percentage of adults who do no leisure-time activity.

• Increase access to employee-based exercise facilities and programs.

A national goal is to increase the proportion of people who regularly

perform flexibility exercises. Why is flexibility exercise often not

prioritized in an exercise program, even by regular exercisers? What

specific benefits would you gain from flexibility exercise?

cor22568_ch10_199-224.indd 213 10/09/12 7:00 PM

F O S T E R , C E D R I C 1 6 9 2 T S

214

T a

b le

Trapezius

Table 3 The Basic Eight for Trunk Stretching Exercises 1. Upper Trapezius/Neck

Stretch

This exercise stretches the muscles on the back and sides of the neck. To stretch the right trapezius, place left hand on top of your head. Gently look down toward your left underarm, tucking your chin toward your chest. Let the weight of your arm gently draw your head for- ward. Hold. Repeat to the opposite side.

Variations: The stretch above may be modifi ed to stretch the muscles on the front and sides of the neck. Start from the stretch position described above. Keep your

left ear near your left shoulder. Turn your head slightly and look up

toward the ceiling, lifting your chin 2–3″. Hold.

3. Pectoral Stretch

This exercise stretches the chest muscles (pectorals). 1. Stand erect in doorway, with arms raised 45 degrees,

elbows bent, hands grasping the doorjamb, and feet in front-stride position. Press out on door frame, con- tracting your arms maximally for 6 seconds. Relax and shift weight forward on legs. Lean into doorway, so that the muscles on the front of your shoulder joint and chest are stretched. Hold.

2. Repeat with your arms raised 90 degrees.

3. Repeat with your arms raised 135 degrees. This exercise is useful to prevent or correct round shoulders and sunken chest.

2. Chin Tuck

This exercise stretches the muscles at the base of the skull and reduces headache symptoms. Sit up

straight, with chest lifted and shoulders back. Gently tuck in

the chin by making a slight motion of nodding “yes.” Imagine a string attached to the back of your head, which is pulling your head upward, like a puppet. As your chin draws inward, attempt to lengthen the back of your neck. Hold.

4. Lateral Trunk Stretch

This exercise stretches the trunk muscles. Sit on the floor. Stretch the left arm over your head, to the right. Bend to the right at the waist, reaching as far to the right as pos-

sible with your left arm and as far as possible to the left with your right arm; hold. Do not let your trunk rotate. Repeat on

the opposite side. For less stretch, your overhead

arm may be bent at the elbow. This exercise can be done in the standing posi- tion, but is less effective.

Longissimus capitis

Semispinalis capitis

Splenius capitis

Semispinalis cervicis

Pectoralis major

Pectoralis minor

Latissimus dorsi

VIDEO 5

cor22568_ch10_199-224.indd 214 17/08/12 9:25 PM

F O S T E R , C E D R I C 1 6 9 2 T S

215

T a

b le

Erector spinae

Gluteus maximus

5. Leg Hug

This exercise stretches the hip and back extensor muscles. Lie on your back. Bend one leg and grasp your thigh under the knee. Hug it to your chest. Keep the other leg straight and on the floor. Hold. Repeat with the opposite leg.

7. Trunk Twist

This exercise stretches the trunk muscles and the muscles on the outside of the hip. Sit with your right leg extended, left leg bent and crossed over the right knee. Place your right arm on the left side of the left leg and push against that leg while turning the trunk as far as possible to the left. Place the left hand on the floor behind the but- tocks. Stretch and hold. Reverse position and repeat on the opposite side.

The Basic Eight for Trunk Stretching Exercises Table 3

8. Spine Twist

This exercise stretches the trunk rotators and lateral rotators of the thighs. Start in hook-lying position, arms extended at shoulder level. Cross your left knee over the right. Push the right knee to the floor, using the pressure of the left knee and leg. Keep your arms and

shoulders on the floor while touch- ing your knees to the floor on the

left. Stretch and hold. Reverse leg position and lower your knees to right.

6. Heel Si t

This exercise stretches the muscles of the lower back. Begin on hands and knees with eyes looking down toward the floor. Keep your hands on the floor directly below your shoulders. Rock backwards, bringing your buttocks toward your heels. Gently round the lower back outward. Hold.

Erector spinae

Gluteus maximus

Latissimus dorsi

Gluteals

Erector spinae

Back extensors

cor22568_ch10_199-224.indd 215 17/08/12 9:25 PM

F O S T E R , C E D R I C 1 6 9 2 T S

216

T a

b le

Gastrocnemius

Shin muscles

Table 4 The Basic Eight for Leg Stretching Exercises

1. Calf Stretch

This exercise stretches the calf muscles and Achilles tendon. Face a wall with your feet 2′ or 3′ away. Step forward on your left foot to allow both hands to touch the wall. Keep the heel of your right foot on the ground, toe turned in slightly, knee straight, and buttocks tucked in. Lean forward by bending your front knee and arms and allowing your head to move nearer the wall. Hold. Bend your right knee, keeping your heel on fl oor. Stretch and hold. Repeat with the other leg.

3. Back-Saver Hamstring Stretch

This exercise stretches the hamstrings and calf muscles and helps prevent or correct backache caused in part by short hamstrings. Sit on the fl oor with the feet against the wall or an immovable object. Bend left knee and bring foot close to buttocks. Clasp hands behind back. Contract the muscles on the back of the upper leg (ham- strings) by pressing the heel downward toward the fl oor; hold; relax. Bend forward from hips, keeping lower back as straight as possible. Let bent knee rotate outward so trunk can move forward. Lean forward keeping back fl at; hold and repeat on each leg.

2. Shin Stretch

This exercise relieves shin muscle soreness by stretch- ing the muscles on the front of the shin. Kneel on both knees, turn to the right, and press down and stretch

your right ankle with your right hand. Move your pelvis forward. Hold.

Repeat on the opposite side. Except when they are sore, most

people need to strengthen rather than stretch these

muscles.

4. Hip and Thigh Stretch

This exercise stretches the hip (iliopsoas) and thigh mus- cles (quadriceps) and is useful for people with lordosis and back prob- lems. Place your right knee directly above your right ankle and stretch your left leg backward so your knee touches the fl oor. If necessary, place your hands on fl oor for balance.

1. Tilt the pelvis backward by tucking in the abdomen and flattening the back.

2. Then shift the weight for- ward until a stretch is felt on the front of the thigh; hold. Repeat on the opposite side. Caution: Do not bend your front knee more than 90 degrees.

Hamstrings

2 1

Iliopsoas

Quadriceps

VIDEO 6

cor22568_ch10_199-224.indd 216 17/08/12 9:25 PM

F O S T E R , C E D R I C 1 6 9 2 T S

217

T a

b le

5. Sitting Stretch

This exercise stretches the muscles on the inside of the thighs. Sit with the soles of your feet together; place your hands on your knees or ankles and lean your fore- arms against your knees; resist (contract) by attempting to raise your knees. Hold. Relax and press the knees toward the fl oor as far as possible; hold. This exercise is

useful for pregnant women and anyone whose thighs tend to

rotate inward, causing back- ache, knock-knees, and

fl at feet.

7. Inner Thigh Stretch

This exercise stretches the muscles of the inner thigh. Stand with feet spread wider than shoulder-width apart. Shift weight onto the right foot and bend the right knee slightly. Straighten left knee and raise toes of left foot off the fl oor. Lean forward slightly from the waist keeping back straight/shoulders back. Shift weight back over the

right foot by moving hips diagonally away from the left foot. Hold.

Repeat in the opposite direction.

The Basic Eight for Leg Stretching Exercises Table 4

6. Lateral Thigh and Hip Stretch

This exercise stretches the muscles and connective tis- sue on the outside of the legs (iliotibial band and tensor fascia lata). Stand with your left side to the wall, left arm extended and palm of your hand fl at on the wall for support. Cross the left leg behind the right leg and turn the toes of both feet out slightly. Bend your left knee slightly and shift your pelvis toward the wall (left) as your trunk bends toward the right. Adjust until tension is felt down the outside of the left hip and thigh. Stretch and hold. Repeat on the other side.

Adductors

Iliotibial band

Piriformis Superior gemellus

Obturator internus Inferior gemellus

Adductors

8. Deep Buttock Stretch

This exercise stretches the deep buttock muscles, such as the piriformis. Lie on your back with knees bent and one ankle crossed over opposite knee. Hold thigh of bottom leg and pull gently toward your chest. Hold. Repeat on the other side.

cor22568_ch10_199-224.indd 217 17/08/12 9:25 PM

F O S T E R , C E D R I C 1 6 9 2 T S

218

T a

b le

Triceps

Latissimus dorsi

Posterior Cuff

Forearm flexor or extensors

Table 5 The Basic Four for Arm Stretching Exercises

1. Forearm Stretch

This exercise stretches the muscles on the front and back sides of the lower arm. It is particularly useful in relieving stress from excessive keyboarding activity. Hold your right arm straight out in front, with your palm facing down. Use your left hand to gently stretch the fi ngertips of your right hand toward the fl oor. Hold. Turn your right arm over with your palm facing up. Use your

left hand to gently stretch the fi ngertips of your right hand toward the fl oor. Hold. Repeat on the opposite side.

2. Back Scratcher

Stand straight with back of left hand held fl at against back. With right hand, throw one end of a towel over right shoulder from front to back. Grab end of towel with

left hand. Pull down gently on the towel with right hand, rais-

ing arm in back as high as is comfortable. Hold. Repeat

to opposite side.

3. Overhead Arm Stretch

This exercise stretches the triceps and latissimus dorsi muscles. Stretch your arms up

overhead. Grasp your right elbow with your left hand.

Pull your right elbow back behind your head. Hold. Repeat on opposite side.

4. Arm Pretzel

This exercise stretches the shoulder muscles (lateral rotators). Stand or sit with your elbows fl exed at right angles, palms up. Cross your right arm over your left; grasp your right thumb with your left hand and pull gen-

tly downward, causing your right arm to rotate laterally. Stretch and hold.

Reverse arm position and repeat on your left arm.

Pectoralis Deltoid

cor22568_ch10_199-224.indd 218 17/08/12 9:26 PM

F O S T E R , C E D R I C 1 6 9 2 T S

L a

b R

e s o

u rc

M a

te ria

219

F le

xib ility Te

sts

Lab Resource Materials: Flexibility Tests

Directions: To test the flexibility of all joints is impractical. These tests are for joints used frequently. Follow the instructions carefully. Determine your flexibility using Chart 1.

Test

1. Modified Sit-and-Reach (Flexibility Test of Hamstrings)

a. Remove shoes and sit on the floor. Place the sole of the foot of the extended leg flat against a box or bench. Bend opposite knee and place the head, back, and hips against a wall with a 90-degree angle at the hips.

b. Place one hand over the other and slowly reach forward as far as you can with arms fully extended. Keep head and back in contact with the wall. A partner will slide the measuring stick on the bench until it touches the fingertips.

c. With the measuring stick fixed in the new posi- tion, reach forward as far as possible, three times, holding the position on the third reach for at least 2 seconds while the partner records the distance on the ruler. Keep the knee of the extended leg straight (see illustration).

d. Repeat the test a second time and average the scores of the two trials.

Test

2. Shoulder Flexibility (“Zipper” Test)

a. Raise your arm, bend your elbow, and reach down across your back as far as possible.

b. At the same time, extend your left arm down and behind your back, bend your elbow up across your back, and try to cross your fingers over those of your right hand as shown in the accompanying illustration.

c. Measure the distance to the nearest half-inch. If your fingers overlap, score as a plus. If they fail to meet, score as a minus; use a zero if your fingertips just touch.

d. Repeat with your arms crossed in the opposite direction (left arm up). Most people will find that they are more flexible on one side than the other.

VIDEO 7

cor22568_ch10_199-224.indd 219 17/08/12 9:26 PM

F O S T E R , C E D R I C 1 6 9 2 T S

220

L a

b R

e s o

u rc

M a

te ri

a ls

F le

xi b

ili ty

T e st

s Test

3. Hamstring and Hip Flexor Flexibility

a. Lie on your back on the floor beside a wall.

b. Slowly lift one leg off the floor. Keep the other leg flat on the floor.

c. Keep both legs straight.

d. Continue to lift the leg until either leg begins to bend or the lower leg begins to lift off the floor.

e. Place a yardstick against the wall and under- neath the lifted leg.

f. Hold the yardstick against the wall after the leg is lowered.

g. Using a protractor, measure the angle created by the floor and the yardstick. The greater the angle, the better your score.

h. Repeat with the other leg.* *Note: For ease of testing, you may want to draw angles on a piece of

posterboard, as illustrated. If you have goniometers, you may be taught to

use them instead.

Test

4. Trunk Rotation

a. Tape two yardsticks to the wall at shoulder height, one right side up and the other upside down.

b. Stand with your left shoulder an arm’s length (fist closed) from the wall. Toes should be on the line, which is perpendicular to the wall and even with the 15-inch mark on the yardstick.

c. Drop the left arm and raise the right arm to the side, palm down, fist closed.

d. Without moving your feet, rotate the trunk to the right as far as possible, reaching along the yard- stick, and hold it 2 seconds. Do not move the feet or bend the trunk. Your knees may bend slightly.

e. A partner will read the distance reached to the nearest half-inch. Record your score. Repeat two times and average your two scores.

f. Next, perform the test facing the opposite direc- tion. Rotate to the left. For this test, you will use the second yardstick (upside down) so that, the greater the rotation, the higher the score. If you have only one yardstick, turn it right side up for the first test and upside down for the second test.

15-inch mark

Chart 1 Flexibility Rating Scale for Tests 1–4

Men Women

Classification Test 1 Test 2 Test 3 Test 4 Test 1 Test 2 Test 3 Test 4

Right

Left

Right

Left

High performance* 16+ 5+ 4+ 111+ 20+ 17+ 6+ 5+ 111+ 20.5 or >

Good fitness zone 13–15 1–4 1–3 80–110 16–19.5 14–16 2–5 2–4 80–110 17–20

Marginal zone 10–12 0 0 60–79 13.5–15.5 11–13 1 1 60–79 14.5–16.5

Low zone <9 <0 <0 <60 <13.5 <10 <1 <1 <60 <14.5

*Though performers need good flexibility, hypermobility may increase injury risk.

cor22568_ch10_199-224.indd 220 17/08/12 9:26 PM

F O S T E R , C E D R I C 1 6 9 2 T S

221

L a

b 1

0 A

E va

lu a tin

g F

le xib

ility

Lab 10A Evaluating Flexibility

Name Section Date

Purpose: To evaluate your flexibility in several joints

Procedures

1. Take the flexibility tests outlined in Lab Resource Materials, pages 219–220. 2. Record your scores in the Results section. 3. Use Chart 1 in Lab Resource Materials (page 218) to determine your ratings on the self-assessments; then place

an X over the circle for the appropriate rating.

Results

Flexibility Scores and Ratings

Record Scores Record Ratings

High Performance Good Fitness Marginal Low

Modified sit-and-reach

Test 1 Left

Right

Zipper

Test 2 Left

Right

Hamstring/hip flexor

Test 3 Left

Right

Trunk rotation

Test 4 Left

Right

cor22568_ch10_199-224.indd 221 17/08/12 9:26 PM

F O S T E R , C E D R I C 1 6 9 2 T S

222

L a

b 1

0 A

E va

lu a ti n g

F le

xi b

ili ty

Do any of these muscle groups need stretching? Check yes or no for each muscle group.

Yes No

Back of the thighs and knees (hamstrings)

Calf muscles

Lower back (lumbar region)

Front of right shoulder

Back of right shoulder

Front of left shoulder

Back of left shoulder

Most of the body

Trunk muscles

Conclusions and Implications: In several sentences, discuss your current flexibility and your flexibility needs for the future. Include comments about your current state of flexibility, need for improvement in specific areas, and special flexibility needs for sports or other special activities.

cor22568_ch10_199-224.indd 222 17/08/12 9:26 PM

F O S T E R , C E D R I C 1 6 9 2 T S

223

Chart 1 Stretching Exercise Survey

1. Determine your current stage for flexibility exercise. Check only the stage that represents your current activity level.

Precontemplation. I do not meet flexibility exercise guidelines and have not been thinking about starting.

Contemplation. I do not meet flexibility exercise guidelines but have been thinking about starting.

Preparation. I am planning to start doing regular flexibility exercises to meet guidelines.

Action. I do flexibility exercises, but I am not as regular as I should be.

Maintenance. I regularly meet guidelines for flexibility exercises.

2. What are your primary goals for flexibility exercise?

General conditioning

Sports improvement (specify sport:___________________)

Health benefits

3. Are you currently involved in a regular stretching program? If yes, describe your program. If no, describe barriers that have prevented you from stretching.

Yes

L a

b 1

0 B

P la

n n in

g a

n d

L o

g g

in g

S tre

tc h in

g E

xe rc

ise s

Lab 10B Planning and Logging Stretching Exercises

Name Section Date

Purpose: To set 1-week lifestyle goals for stretching exercises, to prepare a stretching for flexibility plan, and to self-monitor progress in your 1-week plan

Procedures

1. Using Chart 1, provide some background information about your experience with stretching exercise, your goals, and your plans for incorporating these exercises into your normal exercise routine.

2. In Chart 2, keep a log of your actual participation in stretching exercise. You can choose from any of the stretching exercises described in Table 3, 4, or 5. Try to pick at least eight exercises and perform them at least 3 days in the week (ideally every day).

3. Describe your experiences with your stretching exercise program. Be sure to comment on your plans for future stretching exercise.

Results Yes No

Did you do eight exercises at least 3 days in the week?

Did you do eight exercises more than 3 days in the week?

cor22568_ch10_199-224.indd 223 17/08/12 9:26 PM

F O S T E R , C E D R I C 1 6 9 2 T S

224

L a

b 1

0 B

P la

n n in

g a

n d

L o

g g

in g

S tr

e tc

h in

g E

xe rc

is e s

Conclusions and Interpretations

1. Do you feel that you will use stretching exercises as part of your regular lifetime physical activity plan, either now or in the future? Use several sentences to explain your answer.

Chart 2 Stretching Exercise Log

List the stretching exercises you

actually performed and the days

on which you performed them.

Day 1

Date:

Day 2

Date:

Day 3

Date:

Day 4

Date:

Day 5

Date:

Day 6

Date:

Day 7

Date:

2. Discuss the exercises you feel benefited you and the ones that did not. What exercises would you continue to do and which ones would you change? Use several sentences to explain your answer.

cor22568_ch10_199-224.indd 224 17/08/12 9:26 PM

F O S T E R , C E D R I C 1 6 9 2 T S

Body Mechanics: Posture, Questionable Exercises, and Care of the Back and Neck

LEARNING OBJECTIVES

After completing the study of this concept, you will be able to:

▶ Identify and describe the anatomy and function of the spine. ▶ Identify and describe the anatomy and function of core muscles. ▶ Clarify the causes and consequences of back and neck pain. ▶ Describe how to prevent and rehabilitate back and neck problems. ▶ Explain why posture is important to neck and back health and ways to improve posture.

▶ Explain why good body mechanics is important to neck and back health and ways to improve body mechanics.

▶ Indicate the exercise guidelines for back health and ways to implement the guidelines.

▶ Name questionable exercises and safer alternatives. ▶ Determine self-assessments to identify potential back, neck, and posture problems and risks, and plan a self-monitored personal program that includes exercises for reducing these problems.

C o

n c

e p

t 1 1

Physical Activity: Special Considerations ▶ Section IV

225

The health, integrity, and

function of the neck and back are

influenced by modifiable as well as

nonmodifiable factors. Maintaining

a healthy neck and back can be

attained by using good posture, good

body mechanics, and safe exercise

technique.

cor22568_ch11_225-264.indd 225 17/08/12 9:29 PM

F O S T E R , C E D R I C 1 6 9 2 T S

226 Section 4 ▶ Physical Activity: Special Considerations

unique structure of the intervertebral discs is critical in distributing force and absorbing shock. The bony structure of the spine bears loads and provides protection to the spinal cord and spinal nerves. Poor posture and poor body mechanics can damage discs and vertebrae, resulting in pain and disability.

Anatomy and Function of the Core Musculature The core is part of an integrated system that

provides stability to the spine. The core includes mus- culature of the abdominals, back extensors, lateral trunk flexors, diaphragm, pelvic floor, and hips. A few of the more familiar muscles of the core include the lumbar mul- tifidus, transversus abdominis, and internal oblique. There is no definitive list of muscles belonging to the core. Some sources may describe the core in terms of 6 or fewer key

T he neck and back serve vital roles in supporting the weight of the head and body, producing movement,

carrying loads, and protecting the spinal cord and nerves. These roles are facilitated by optimal alignment of the vertebrae and a balance between muscular strength and flexibility. Impairment of one or more of these functions can lead to injuries to the muscles, vertebrae, discs, liga- ments, or nerves of the spine. Neck and back pain are common in today’s society, with nearly 80 percent experi- encing an episode of low back pain sometime in life. Back pain is second only to headache as a common medical complaint, and an estimated 30 to 70 percent of Americans have recurring back problems. The multiple functions of the spinal column may predispose this area to injuries. The spine helps to produce an array of movements while bearing significant loads.

Chronic back and neck pain are associated with many personal health problems. Some cases of back pain are “idio- pathic” (no known cause), but some are clearly preventable. This concept provides information about the interrelated function of the spine and trunk musculature. Specific infor- mation about core training, posture, body mechanics, and safe exercise performance will help you adopt preventive measures that may reduce your risk for back and neck prob- lems. As this information is intended to provide a basic foun- dation of knowledge, persons with neck or back pain should always seek direction from their own medical provider.

Anatomy and Function of the Spine The spinal column is arranged for movement. The bones that make up the spine are called vertebrae. There are 33 vertebrae in the spine, and most are separated from one another by an intervertebral disc (see Figure 1 ). The vertebrae are divided into three main regions commonly referred to as cervical (neck), thoracic (upper back), and lumbar (low back). The fused vertebrae that form the tailbone are called the sacrum and coccyx. The connec- tions among the vertebrae of the cervical, thoracic, and lumbar spine allow the trunk to move in complex ways. The spine is capable of flexion (forward bending), exten- sion (backward bending), side bending, and rotation, but functionally, these movements often occur in combina- tion. For example, in executing a tennis serve, the spine both extends and rotates. The spine is at risk for injury when movements are performed repetitively, performed beyond a joint’s healthy range of motion, or performed under conditions of heavy or inefficient lifting.

The spinal column has an important role in bearing

loads and protecting the neck and back from

injury. The widest portion of each vertebra articulates with the intervertebral disc to form a strong pillar of support extending from the skull to the pelvis. The

Figure 1 ▶ Curvatures of the spinal column.

Cervical lordotic curve

C7 T1

T12

S1 L5

Thoracic kyphotic curve

Lumbar lordotic curve

sacrum

coccyx

vertebrae intervertebral disc

cor22568_ch11_225-264.indd 226 17/08/12 9:30 PM

F O S T E R , C E D R I C 1 6 9 2 T S

Concept 11 ▶ Body Mechanics: Posture, Questionable Exercises, and Care of the Back and Neck 227

muscle groups, while other sources may include as many as 20 different muscle groups. Regardless, muscles of the core all share a common anatomical trait: their location and attachment to either the spine, pelvis, or rib cage. Col- lectively, the core musculature form a three-dimensional cylinder that encompasses the body’s center of gravity. This three-dimensional cylinder is inclusive of the lumbar spine, pelvis, and hips (see Figure 2 ).

Core stability refers to the body’s ability to main-

tain the spine in a “neutral” postural zone, one in

which the physiologic load on the spine is mini-

mized. The overall function of the spinal stabilization system depends on the contribution of three components: a passive restraint system (ligaments, discs, vertebrae, and joints), active restraint system (muscle-tendon units), and neural control system (proprioception and feed-forward mechanisms of the nervous system). Core muscles incorporate functions of both the active restraint and neural control systems to maintain ideal postural align- ment, thereby minimizing excessive stress and strain to the spine.

Muscles of the core are commonly classified as

either mobilizers or stabilizers. In general, the mobi- lizers are those muscles that are more superficial and contract concentrically to produce trunk movements. The stabilizers are muscles that are more deeply located and contract isometrically or eccentrically to stabilize the trunk during arm and leg movements. The stabilizer

group is further divided into two categories, local and global. These groups are distinguished by differences in anatomy and function.

The local core stabilizers provide stiffness and stabil- ity to the spine. They include muscles that possess a small cross-sectional area, are deeply located, and may span just one or two vertebral levels at a time. Functionally, these muscles provide local spinal support, control motion between adjacent vertebrae, increase intra-abdominal pressure, and provide proprioceptive input to the body to avoid injury. The most notable example of a local core stabilizer is the lumbar multifidus. Also included in the group are muscles that indirectly influence the stability of the spine due to their role in increasing intra-abdominal pressure and their supportive attachment to the fascia of the back. These muscles include the transversus abdomi- nis, internal oblique, diaphragm, and pelvic floor muscles. The local core muscles are believed to maintain the spine in “neutral” via isometric co-contractions, thereby mini- mizing excessive loading of the spine.

Intervertebral Discs Spinal discs; cushions of car- tilage between the bodies of the vertebrae. Each disc consists of a fibrous outer ring (annulus fibrosus) and a pulpy center (nucleus pulposus). Local Core Stabilizers Deep core muscles that provide stiffness and stability to the spine.

Figure 2 ▶ Cross section showing layers of core musculature.

External oblique

Rectus abdominis

Quadratus lumborum

Erector spinae

MultifidusPsoas major

Lumbar spine (L3)

Multifidus

Internal oblique

Transversus abdominis

Muscles of pelvic floor

cor22568_ch11_225-264.indd 227 17/08/12 9:30 PM

F O S T E R , C E D R I C 1 6 9 2 T S

228 Section 4 ▶ Physical Activity: Special Considerations

The global core stabilizers function to produce trunk motion as well as trunk stability based on their attach- ments to the pelvis. These muscles tend to have a larger cross-sectional area, are more superficially located, often span multiple vertebral levels, and possess attachments to the pelvis, rib cage, and/or thoracic spine. Examples include the rectus abdominis, exter- nal oblique, quadratus lumborum, and erector spinae. Also included are muscles of the hip, which indi- rectly influence lumbar stability by altering tilt of the pelvis. Functionally the global core stabilizers generate movement of the trunk as well as provide stabilization.

Causes and Consequences of Back and Neck Pain Most back and neck pain stems from lifestyle

choices or life experiences. The original cause (or causes) of back and neck pain are typically hard to iden- tify. Although back and neck problems can result from an acute injury (e.g., a diving accident or car accident), most are caused by accumulated stresses over a lifetime. These factors include the avoidable effects of poor posture and body mechanics as well as questionable exercises that put the back at risk. (Exercises to avoid are discussed later in the concept.) Musculoskeletal injuries and degenerative changes to the discs, vertebrae, joint surfaces, muscles, or ligaments can predispose you to back and neck problems. Depression, cancer, infections, and some visceral dis- eases (kidney, pelvic organs) can also contribute to back problems. Although people have some control over these causes, some back pain stems directly from structural or functional disorders that a person is born with. Inherited causes include anomalies of the spine and some forms of scoliosis .

To reduce risk for back pain, reduce the risk factors that you have control over. Modifiable risk factors (fac- tors you can change) include regular heavy labor, use of vibrational tools, routines of prolonged sitting, smoking, a hypokinetic lifestyle, coronary artery disease, and obe- sity. Nonmodifiable risk factors include a family history of joint disease, age, congenital anomalies, and direct trauma (e.g., a fall or rough athletic activity when young). Lab 11A provides a questionnaire for assessing your potential risk for back and neck pain.

The nervous system and various pain-sensitive

structures contribute to back pain. Back pain can result from direct or indirect causes. Direct causes are typically the result of tissue trauma to areas in or around the spinal column. The most common sources of pain are ligaments, intervertebral discs, nerve roots, spinal joints, and muscles. Indirect causes stem from the release of pain-causing chemicals from injured tissues. These

Health is available to Everyone

for a Lifetime, and it’s Personal

Is Back Pain in Your Future?

According to the National Institutes of Health, the most common medical problem in the United States is back pain, which is very often caused by degeneration of the disks in the spine. Preventative measures include main- taining a healthy weight over the lifespan, using proper lifting techniques, and engaging in regular exercise, par- ticularly strength training and flexibility exercises.

What steps are you taking today to help prevent back problems

later in life?

ACTIVITY

A CLOSER LOOK

ACTIVITY

Functional Fitness Predicts Injury Risk Being physically fit provides many health benefits but studies have typically not shown that fitness can reduce risk of inju- ries. This is because many injuries often happen dynamically and acutely. However, several recent studies demonstrate the utility of a specific screening protocol—the Functional Move- ment Screen (FMS)—that can diagnose limitations and imbal- ances that may predispose a person to injury. To address these problems, functional fitness training tends to rely on large, multi-planar movements of the limbs that indirectly target core muscles. The deep core muscles are known to

contract in anticipation of most arm and leg movements. By contracting prior to arm or leg movement, the deep core mus- cles act as a brace around the trunk and a solid anchor from which powerful arm and leg movements can occur. By utilizing functional fitness training techniques, the core musculature can be better prepared to handle the forces, postures, and actions involved in real-life activities and sports.

Do you think you have sufficient functional fitness for your lifestyle?

Why or Why not?

VIDEO 1

cor22568_ch11_225-264.indd 228 17/08/12 9:30 PM

F O S T E R , C E D R I C 1 6 9 2 T S

Concept 11 ▶ Body Mechanics: Posture, Questionable Exercises, and Care of the Back and Neck 229

chemicals cause nerves in the area to remain irritated and sensitive. Processes within the brainstem, spinal cord, and peripheral nerves can also modulate the sensation of pain, either increasing or decreasing it. For example, some back pain can be caused by abnormal feedback loops that enhance or maintain the perception of pain—even when the original cause or problem is corrected.

The integrity of the neck and back are jeopardized

by excessive stress and strain. Forces are constantly at work to bend, twist, shear, compress, or lengthen tis- sues of the body. Stress on these tissues may eventually create strain, a change in the tissue’s size or dimension. Healthy tissues typically return to their normal state once the force is removed. Injury occurs when excessive stress and strain prevent the tissue from returning to its normal state. A number of factors can contribute to stress and strain on the back.

• Poor posture can cause body segments to experience stress and strain. When body segments are in poor align- ment (e.g., slouching or forward head positions), the muscles in the back and neck must work hard to com- pensate. This creates excessive stress and strain in the affected area(s). Over time, tension in these muscles can lead to myofascial trigger points , causing head- ache or referred pain in the face, scalp, shoulder, arm, and chest. The chronic stress from poor alignment can also lead to other postural deviations and degenerative changes in the neck.

• Prolonged sitting contributes to back problems. Sitting, by itself, is not a risk factor for the development of back pain. However, when prolonged sitting (more than half the work day) is combined with exposure to vibra- tion and awkward postures at work, an individual has four times the risk of developing back pain. Occupa- tions with the highest risk based on these three factors include helicopter pilots and truck drivers.

• Bad body mechanics and improper lifting techniques con- tribute to stress and strain on the spine. The lumbar verte- brae and the sacrum are most vulnerable to this type of injury due to the significant weight they support and the thinner ligamentous support at this level.

• Being overweight or obese increases the risk of back pain. Those who are obese are on average 20 percent more likely to have back pain than those of normal weight. Obesity and overweight status are hard on the body because they overload the bones, discs, tendons, and ligaments of the body. Added wear and tear on joint sur- faces can lead to osteoarthritis. Postural changes accom- pany weight gain and create additional stress and strain on joints. For example, a large protruding abdo- men often causes forward tipping of the pelvis and excessive arching of the low back that can lead to back pain.

Some exercises and movements can produce

microtrauma, which can lead to back and neck

pain. Most people are familiar with acute injuries, such as ankle sprains. These injuries are associated with immediate onset of pain and swelling. Microtrauma is a “silent injury”—a subtle form of injury that results from accumulated damage over time. It can result from repetitive motion, repeated forceful exertion, long-term vibration or working with awkward postures. When microtrauma occurs as the result of activities at work, it is often referred to by the medical terms Repetitive Stress Injury (RSI) or Cumulative Trauma Disorder (CTD). One common example is carpal tunnel syndrome, a painful irritation of the median nerve at the wrist, often brought on by repetitive motion of the wrist during long and extended periods of typing, assembly line tasks, or construction work.

Microtrauma can also result from the repetitive per- formance of unsafe exercises or contraindicated move- ments. For example, regular performance of full deep knee squats or full neck circles may irritate the joint sur- faces and eventually cause knee or neck pain. Repeated overhead lifting with excessive loads can irritate and dam- age the rotator cuff tendon of the shoulder. The initial wear and tear of microtrauma is not something typically noticed. However, over many years, microscopic changes occur in the joint. Examples include swelling, fibrosis of the synovial lining, abnormal thickening of the surround- ing joint capsule, calcifications in the tendons, and thin- ning and roughening of the cartilage cushioning the joint surfaces. Because these changes are unseen and often unfelt, the offending exercise or activity is often viewed as harmless. However, later in life the effects from the microtrauma become more apparent, manifesting in ten- donitis, bursitis, arthritis, or nerve compression. Chances are, when the injury reaches a painful stage, the cause is not identified and it gets attributed to aging.

Global Core Stabilizers Superficial core muscles that produce motion and aid in stabilization. Scoliosis A curvature of the spine that produces a sideways curve with some rotation; while typically mild, this condition can sometimes be painful. Myofascial Trigger Points Tender spots in the muscle or muscle fascia that refer pain to a location distant to the point. Referred Pain Pain that appears to be located in one area, though it actually originates in another area. Microtrauma Injury so small it is not detected at the time it occurs.

cor22568_ch11_225-264.indd 229 17/08/12 9:30 PM

F O S T E R , C E D R I C 1 6 9 2 T S

230 Section 4 ▶ Physical Activity: Special Considerations

Degenerative disc disease is a common part of

aging and a source of back pain. Many elderly adults get shorter as they age, often due to degenerative changes within the vertebral bodies and discs. One notable change is flattening of the discs as a result of lost water content. This reduces the space between vertebrae and increases the compressive forces on the small facet joints and the large vertebral bodies. This results in a decrease in the size of the spinal canal, which in turn increases the likeli- hood of nerve impingement, bone spur development, and arthritis, all of which can contribute to back pain and dis- ability (see Figure 4 ).

Injury to the spine negatively affects the function

of the core musculature. One of the more important core muscles, the lumbar multifidus, is adversely affected by back pain. Studies demonstrate that with low back pain, the muscle becomes inhibited (exhibiting decreased levels of activation and increased fatigability), is subject to atrophy, and becomes infiltrated with fatty deposits. In the healthy individual, the multifidus is believed to be responsible for providing more than two-thirds of the dynamic rigidity to the lumbar spine and serves an important role in proprioception and kinesthetic aware- ness. Research studies have shown specific spinal sta- bilization exercises to be effective in reversing some of the adverse changes to the multifidus, including positive

The lumbar intervertebral discs are particularly

susceptible to injury and herniation. The interverte- bral discs located between the vertebrae of the spine are composed of a tirelike outer ring (annulus fibrosus) sur- rounding a gel-like center (nucleus pulposus). The great- est risk for injury to the discs occurs during excessive loading and twisting motions of the spine. While most people think that disc injuries occur from an acute injury, disc herniation typically reflects a degenerative process that takes place over time. With repeated microtrauma, small tears begin to occur in the inner fibers of the annu- lus. The nucleus begins to move outward ( herniated disc ), much like toothpaste moving within a squeezed tube. Disc herniation is termed incomplete or contained as long as the migrating edge of the nucleus remains within the fibers of the annulus. As damage continues (often the result of years of cumulative microtrauma), the annular fibers may reach a point of rupture at their periphery (see Figure 3 ). At this point (termed disc extrusion ), the nucleus pulposus moves into the space around the spinal cord or nerve root. At this stage, herniation is termed complete or noncontained.

The risk of disc herniation is greater for younger

adults. Disc herniation is frequently listed as a cause of back pain, but studies show that only 5 to 10 percent of persons with herniated discs experience pain. The reason for this is that pain is often not experienced until com- plete herniation occurs. Pain is felt as the nuclear mate- rial begins to press on pain-sensitive structures in its path. Interestingly, the risk for disc herniation is greatest for individuals in their 30s and 40s. Risk decreases with age as the disc degenerates and becomes less soft and pliable.

Figure 4 ▶ Normal disc (a) and degenerated disc with nerve impingement and arthritic changes (b). Figure 3 ▶ Normal disc (a) and herniated disc (b).

Spinal nerve

Fibrous ring

(a)

(b)

Spinal cord

Nucleus pulposus

Bulging nucleus presses on spinal nerve

Nerve root

Spinal cord

Narrowed space

Nerve root

Arthritis

Spinal cord

Normal disc

(a)

(b)

Bone spur

Degenerated disc

Body of vertebra

cor22568_ch11_225-264.indd 230 17/08/12 9:30 PM

F O S T E R , C E D R I C 1 6 9 2 T S

Concept 11 ▶ Body Mechanics: Posture, Questionable Exercises, and Care of the Back and Neck 231

gains in cross-sectional area/muscle bulk and improved neural recruitment. More importantly, participation in a program of core training exercise has also been shown to improve pain tolerance and function. Rehabilitation of the lumbar multifidus appears critical in the recovery period following back pain.

Medical intervention is sometimes needed for neck

or back pain. Most cases of back pain resolve spontane- ously, with 70 percent having no symptoms at the end of 3 weeks and 90 percent recovered after 2 months. How- ever, medical approaches have been shown to speed up recovery from acute back/neck pain and to improve pain tolerance and function in chronic cases. Conservative treatment typically involves the use of anti-inflammatory medications, muscle relaxants, heat, cryotherapy, trac- tion, or electrical stimulation. It can also include thera- peutic exercise, massage, and joint mobilization. When this treatment is unsuccessful, referral to an alternative therapy, such as acupuncture, or to a pain clinic for ste- roidal anti-inflammatory injections may occur. As a last measure, surgery may be needed for removal of a herni- ated portion of a disc.

Prevention of and Rehabilitation from Back and Neck Problems Exercise is a frequently prescribed treatment for

back or neck pain. Exercise, such as resistance and aerobic exercises, has been found to be helpful in treating many types of chronic pain. Exercises that are selected specifically to help correct pain-related problems are classified as therapeutic. These exercises are aimed at correcting the underlying cause of neck or back pain by strengthening weak muscles, stretching short ones, and improving circulation to and nourishment of tissues of

the body. Both therapeutic and health-related fitness exercises may be considered preventive. Done faithfully, and with the appropriate FIT formula, they improve the health of the musculoskeletal system, allowing greater efficiency of function and reduced incidence of injury.

Use of specific core stabilization exercises may

reduce low back pain and functional disability. The integrity of individual vertebral segments of the spine is often compromised with injury to the neck or back. One or more components of the passive restraint system (ligaments, discs, vertebrae, or joints) may be damaged, creating a weak link in the stabilization system. In addi- tion, optimal function of the dynamic and neural con- trol systems is often adversely affected by injury. This may make a specific segment of the spine more vulner- able to delayed healing or further injury. Core training may enhance stability to the injured area by improving the function of the dynamic and neural control systems. Core training programs are also effective in treating low back pain. Studies have shown significant improvements in pain level and functional status following a program of spinal stabilization exercises, but positive results have also been obtained from more general exercise interven- tions. Future research may help identify subsets of people who may benefit from one type of exercise program over another.

Core stability training and core strengthening

training can promote good back health. As described in Concept 9, building core strength is important for overall muscular fitness. However, to reduce the risks for back and neck problems, you need to train the muscles involved in core stabilization. There are two main types of core training programs, and each requires somewhat different methods.

Core stability training refers to the training of the deeper (“local”) core musculature. Physiologically, the local core stabilizers are slow-twitch endurance muscles that are poorly recruited, demonstrate low force produc- tion, and often sag/lengthen due to weakness. Training

Herniated Disc The soft nucleus of the spinal disc that protrudes through a small tear in the surround- ing tissue; also called prolapse. Core Strength Strength of muscles that demon- strate optimal firing patterns and tension-generating capabilities to create movement of the trunk. Core Stability Strength of muscles that demon- strate optimal firing patterns and tension-generating capabilities to “brace” the trunk in anticipation of, and during, movement of the head, arms, or legs.

Core stability training can help maintain a healthy back.

cor22568_ch11_225-264.indd 231 17/08/12 9:30 PM

F O S T E R , C E D R I C 1 6 9 2 T S

232 Section 4 ▶ Physical Activity: Special Considerations

principles for the local core stabilizers are based on the respective physiology of the muscles. In general, exercises should involve slow and controlled movements and be held for long durations. The focus should be on improv- ing trunk muscle endurance, since endurance of the trunk musculature appears to be more important than strength for reducing the risk of low back pain. Therefore, exer- cises should emphasize lower resistance and involve more repetitions. Sets of 8 to 12 repetitions at very light to moderate intensity are appropriate for improving the endurance of core stabilizers. Exercises for improving local core stability are described and illustrated in the exercise section at the end of the concept.

Core strength training refers to the training of the more superficial “global” core musculature. Physiologi- cally, these muscles are fast-twitch in nature, contract at higher resistance levels, possess greater potential for force production, work in a noncontinuous fashion, and are preferentially recruited over the local stabilizers. They are often in a shortened (tight) position. Based on the physiologic function of the global core muscles, rec- ommended training principles include shorter duration holds, faster speeds of concentric contractions, greater resistance, and fewer numbers of repetitions. Several sets of exercise (2 to 4 sets of 8 to 12 repetitions at moder- ate to hard intensity) are recommended to improve the core strength of the global core stabilizers. Traditional abdominal and trunk extensor strengthening exercises are included in the exercise section at the end of the concept.

Resistance exercise can often correct muscle

imbalance, the underlying cause of many postural

and back problems. If the muscles on one side of a joint are stronger than the muscles on the opposite side, the body part is pulled in the direction of the stronger muscles. Corrective exercises are usually designed to strengthen the long, weak muscles and to stretch the short, strong ones in order to have equal pull in both directions. For example, people with lumbar lordosis may need to strengthen the abdominals and gluteal muscles and also stretch the lower back and hip flexor muscles.

Although general resistance training may help improve the strength and endurance of the back muscles, the exercises may not be specific enough to target the areas that contribute to risk for low back pain. Because of this, increased attention has been given to the development of back exercise machines that can more effectively rehabili- tate and/or strengthen back musculature. The machines help isolate the muscles by restraining or preventing other muscles from assisting. For example, pelvic muscles are restrained in a back extension machine to help isolate the lumbar muscles. This isolation helps strengthen the lumbar muscles, an important target for reducing risks for back problems.

Good Posture Is Important for Neck and Back Health Good posture has aesthetic benefits. Posture is an important part of nonverbal communication. The first impression a person makes is usually a visual one, and T E C H N O L O G Y U P D A T E

New Training Aids for Core Training Core training is an immensely popular concept across the fields of sport, fitness, and rehabilitation. The popularity of core training programs and classes has led to an expand- ing array of core-training devices and functional fitness classes. One category of devices includes those that provide an unstable surface for challenging balance and stability. Rocker boards, air-filled domes, therapy balls, foam rollers, and sliding disks are a few examples. Par- ticipants creatively position themselves on these devices in various postures—standing, lunging, kneeling, or on hands and knees. A second category of devices includes equipment that provides a dynamic challenge to the arms or legs. Elastic tubing, stretch cords, vibrating wands, kettle bells, and medicine balls are used to overload the extremities and elicit a corresponding and supportive con- traction of the core stabilizers. Creative new devices enter the fitness market on a monthly basis, giving exercise participants fresh new ideas for their workout regimen.

ACTIVITY Movement disciplines like yoga and tai chi can promote body awareness and contribute to back health.

cor22568_ch11_225-264.indd 232 17/08/12 9:30 PM

F O S T E R , C E D R I C 1 6 9 2 T S

Concept 11 ▶ Body Mechanics: Posture, Questionable Exercises, and Care of the Back and Neck 233

good posture can help convey an impression of alertness, confidence, and attractiveness.

Proper posture allows the body segments to be

balanced. Segments of the human body (i.e., the head, shoulder girdle, pelvic girdle, rib cage, and spine) are balanced in a vertical column by muscles and ligaments. Proper posture helps maintain an even distribution of force across the body, improve shock absorption, and minimize the degree of active muscle tension required to maintain upright posture. When viewed from the side, three normal curvatures of the spine are present, causing the vertebral column to appear S-shaped. These curva- tures are created by the lordotic (inward) curve of the cervical and lumbar spines and the kyphotic (outward) curve of the thoracic spine (see Figure 1 ). The curves help balance forces on the body and minimize muscle tension. They are also responsible for humans’ unique ability to walk upright on two legs while maintaining a forward gaze.

The degree of curvature is influenced by the tilt of the pelvis. A forward pelvic tilt increases curvature in the neck and lower back, whereas a backward pelvic tilt flattens the lower back. The most desirable position is a neutral spine in which the spine has neither too much nor too little lordotic curvature. The forces across the spine are balanced and muscular tension is at a minimum.

Awareness of good standing posture is important

to a healthy spine. In the standing position, the head should be centered over the trunk with forward gaze, the shoulders should be down and back but relaxed, with the chest high and the abdomen flat. The spine should have gentle curves when viewed from the side but should be straight when seen from the back. When the pelvis is tilted properly, the pubis falls directly underneath the lower tip of the sternum. The knees should be relaxed, with the knee- caps pointed straight ahead. The feet should point straight ahead or slightly outward, and the weight should be borne over the heel, on the outside border of the sole, and across the ball of the foot and toes (see Figure 5 ).

Awareness of good seated posture is important to

a healthy spine. A large percentage of our days are spent sitting as we attend class, commute to work, sit at a com- puter, dine out, or relax in front of the television. Good seated posture decreases pressure within the discs of the lower back and reduces fatigue of lower back muscles. In sitting, the head should be centered over the trunk, the shoulders down and back. If one is using a computer, the monitor should be at eye level with the screen 18 to 24 inches from the eyes. The seat of the chair should be at an angle that allows the knees to be positioned slightly lower than the hips. The back should firmly rest against the chair, with support to the lumbar spine. The feet

should be supported on the floor and arms supported on armrests for ideal unloading of the spine (see Figure 6 ).

Poor posture contributes to a variety of health

problems. When posture deviates from neutral, weight distribution becomes uneven and tissues are at risk for injury. Examples of common postural deviations are described in Table 1 , along with associated health problems. Two of those highlighted are lumbar lordosis (excessive

Posture The relationship among body parts, whether standing, lying, sitting, or moving. Good posture is the relationship among body parts that allows you to function most effectively, with the least expenditure of energy and with a minimal amount of stress and strain on the body. Lordotic Curve The normal inward curvature of the cervical and lumbar spine. Kyphotic Curve The normal outward curvature of the thoracic spine. Neutral Spine Proper position of the spine to maintain a normal lordotic curve. The spine has nei- ther too much nor too little lordotic curve.

Figure 5 ▶ Comparison of bad and good posture.

Forward head

Kyphosis and sunken chest

Lordosis

Abdominal ptosis

Hyperextended knees

Flat arches

Bad posture Good posture

cor22568_ch11_225-264.indd 233 17/08/12 9:30 PM

F O S T E R , C E D R I C 1 6 9 2 T S

234 Section 4 ▶ Physical Activity: Special Considerations

curvature of the lower back) and flat back (reduced curva- ture of the lower back).

Lumbar lordosis posture occurs when the pelvis is tipped forward from a position of neutral tilt. With this posture, the hip flexor muscles become shortened and tight, while the abdominal muscles become weak and long (with a reduced ability to “hold” within inner range). This muscle imbalance shifts body segment alignment toward a position of uneven loading, increasing pressure on the facet joints of the vertebrae. Over time, degenerative changes may occur, including a narrowing of the openings where spinal nerves exit, thus increasing risk for pain.

Flat back posture, on the other hand, occurs when the pelvis is tipped backward from a position of neutral tilt.

With this posture, the lumbar spine is flexed, the lower back muscles are in a lengthened (weak) position, and the hamstring muscles are shortened and tight. A reduced lumbar curvature increases pressure on the interverte- bral bodies and decreases shock absorption capabilities. Relative differences in flexibility between tight hamstring and long trunk muscles may also increase risk for injury. Laws of physics demonstrate that the body takes the path of least resistance during a chain of movement (e.g., for- ward bending), with the most flexible segment (i.e., the back) providing a greater contribution to the total range of movement. It follows that regions of greater move- ment will experience greater tissue strain. In the case of flat back posture, tight hamstrings may limit the contri- bution of hip motion during forward bending tasks, thus predisposing the lower back to become the fulcrum for movement and the site of injury.

Correcting postural deviations begins with restoring

adequate muscle fitness and muscle length. Most of us have a natural tendency to sit or stand with poor pos- ture. For the most part, we can correct our posture with conscious effort. However, if poor posture is maintained for very long or very frequent periods of time, the body loses resiliency. With poor posture, muscles on one side of a joint or body segment can become shortened or tight while muscles on the opposite side can become lengthened and weak. Poor posture can also result following muscle injury. This may manifest itself in guarded postures or muscle dysfunction, which eventually leads to muscles on one side of the joint becoming inflexible due to facilita- tion and muscles on the opposite side becoming weak due to inhibition. Postural correction can be achieved by

Posture Problem Definition Health Problem

Forward head The head aligned in front of the center of gravity Headache, dizziness, and pain in the neck, shoulders, or arms

Kyphosis Excessive curvature (flexion) in the upper back; also called humpback

Impaired respiration as a result of sunken chest and pain in the neck, shoulders, and arms

Lumbar lordosis Excessive curvature (hyperextension) in the lower back (sway back), with a forward pelvic tilt

Back pain and/or injury, protruding abdomen, low back syndrome, and painful menstruation

Flat back Reduced curvature in the lower back Back pain, increased risk for injury due to reduced shock absorption

Abdominal ptosis Excessive protrusion of abdomen Back pain and/or injury, lordosis, low back syndrome, and painful menstruation

Hyperextended knees The knees bent backward excessively Greater risk for knee injury and excessive pelvic tilt (lordosis)

Pronated feet The longitudinal arch of the foot flattened with increased pressure on inner aspect of foot

Decreased shock absorption, leading to foot, knee, and lower back pain

Table 1 ▶ Health Problems Associated with Poor Posture

Figure 6 ▶ Good sitting posture.

Head centered over trunk

Shoulders down and back

Back against chair

Arms supported on armrest

Knees slightly lower than hips

Feet on floor

cor22568_ch11_225-264.indd 234 17/08/12 9:30 PM

F O S T E R , C E D R I C 1 6 9 2 T S

Concept 11 ▶ Body Mechanics: Posture, Questionable Exercises, and Care of the Back and Neck 235

Good Body Mechanics Is Important for Neck and Back Health Proper body mechanics can help prevent back and

neck injury. Biomechanics is a discipline that applies mechanical laws and principles to study how the body performs more efficiently and with less energy. Good body mechanics, as applied to back care, implies main- taining a neutral spine during activities of daily living. A neutral spine maintains the normal curvature of the spine, thus allowing an optimal balance of forces across the spine, reducing compressive forces, and minimizing muscle tension. In the following sections, specific recom- mendations and examples of good body mechanics are provided for a variety of body positions.

Ergonomics is a discipline that uses biomechanical

principles to develop tools and workplace settings

that put the least amount of strain on the body. Many employers take an active interest in ergonomic principles, since repetitive motion injuries and other musculoskeletal conditions are the leading cause of work-related ill health. Back pain contributes to reduced job productivity, with workers losing an average of 4.6 hours per week of productive time during each episode of back pain. Back pain has societal costs as well. It is the sixth most costly medical condition in the United States, burdening the country with $85.9 billion worth of work expenses each year related to health care, lost income, and lost work productivity. One application of ergonomics (also known as human factors engineering) is the design of effective workstations for computer users. Properly fitting desks and chairs and the effective positioning of computer screens and keyboards can minimize problems such as carpal tunnel syndrome.

Good lifting technique focuses on using the legs. Keep in mind that the muscles of the legs are relatively large and strong, compared with the back muscles. Like- wise, the hip joint is well designed for motion. It is less likely to suffer the same amount of wear and tear as the smaller joints of the spine. When lifting an object from the floor, straddle the object with a wide stance; squat down by hinging through the hips and bending the knees; maintain a slight arch to the lower back by stick- ing out the buttocks; test the load and get help if it is too heavy or awkward; rise by tightening the leg muscles, not the back; keep the load close to the waist; don’t pivot or twist .

Poor body mechanics can increase risks for back

pain. A common cause of backache is muscle strain, fre- quently precipitated by poor body mechanics in daily activities, such as lifting or exercising. If lifting is done improperly, great pressure is exerted on the lumbar discs,

Long/flexible hip flexor muscles

Shortened abdominal muscles

Shortened/strong back muscles

Long/flexible hamstring muscles

Figure 7 ▶ Balanced muscle strength and length permit good postural alignment.

improving body awareness, increasing flexibility of tight muscles, and improving strength of weak (inhibited) mus- cles. For example, a slouched posture with rounded and forward shoulders can be improved by elongating the pec- toralis (chest) muscles and strengthening muscles of the upper back. A lumbar lordosis posture can be improved by stretching the hip flexors and back extensors that keep the top of the pelvis tipped forward, followed by strengthen- ing of the abdominal and gluteal muscles that help tip the pelvis backward (see Figure 7 ).

Hereditary, congenital, and disease conditions,

as well as certain environmental factors, can also

cause poor posture. Some environmental factors that contribute to poor posture include ill-fitting clothing and shoes, chronic fatigue, improperly fitting furniture (including poor chairs, beds, and mattresses), emotional and personality problems, poor work habits, poor physi- cal fitness due to inactivity, and lack of knowledge relating to good posture. Some posture problems, such as scolio- sis, may be congenital, hereditary, or acquired but can be improved with exercise, braces, and/or other medical pro- cedures. Early detection is critical in treating scoliosis.

cor22568_ch11_225-264.indd 235 17/08/12 9:30 PM

F O S T E R , C E D R I C 1 6 9 2 T S

236 Section 4 ▶ Physical Activity: Special Considerations

Figure 8 ▶ Characteristics of good body mechanics for different lifestyle tasks.

Lifting Reaching

Carrying

Pushing & Pulling

Elements of Good Body Mechanics

Do: • Keep a slight arch in the lower back, bend with the knees, straddle and test the load, keep load close to body, tighten abdominals, and lift using legs. • Lower a load using the same principles in reverse.

Don’t: • Bend at the waist. • Twist. • Lift more than you can handle. • Hyperextend the neck or back.

Do: • Use a stool or ladder when working with arms above head level. • Keep tools within easy reach. • Choose tools with extended handles.

Don’t: • Keep arms extended out in front or out to side for long periods of time without rest. • Hyperextend your neck.

Do: • Push or pull heavy objects. • Push rather than pull, if given a choice.

Do: • Keep load midline and close to the body. • Divide the load if possible, carrying half in each arm/hand. • Alternate load from one side of the body to the other when it cannot be divided. • Carry light-moderate loads in a backpack with straps.

cor22568_ch11_225-264.indd 236 17/08/12 9:30 PM

F O S T E R , C E D R I C 1 6 9 2 T S

Concept 11 ▶ Body Mechanics: Posture, Questionable Exercises, and Care of the Back and Neck 237

Sit upright with eyes looking straight ahead, chest lifted, shoulders down and back, slight arch in lower back, knees slightly lower than hips, feet supported on a firm surface. If you cross your legs, alternate which leg is crossed on top. When sitting for longer periods of time, use chair with armrests, an adequate seat cushion and lumbar support. When driving, adjust seat to allow easy reach of foot pedals with slight knee bend; recline seat to allow gentle arch in low back. Reading material should be elevated or supported at eye level. The office desk should be about 29 to 30 inches high for the average man and about 27 to 29 inches high for the average woman. The computer screen should be about 20 to 40 inches away from your eyes with the top of the screen at or slightly below eye level.

Sitting

Standing

Elements of Good Posture

• Use a pillow between the knees when lying on your side and under the knees when lying on the back. • Choose a pillow that supports the head and neck in neutral alignment. • Avoid reading in bed.

Lying

•

• Stand upright with forward gaze, shoulders down and back, chest raised, stomach pulled up and in, slight arch in the lower back, slight bend in the knees, feet shoulder width apart, and toes pointing straight ahead or slightly outward. • If you stand with weight shifted to one side, alternate which leg you lean on. • If you stand in one place for a prolonged time, prop one foot on small step stool. • Height of work surface should be about 2 to 4 inches below the waist.

Figure 9 ▶ Characteristics of good posture for sitting, standing, and lying.

and excessive stress and strain are placed on the lumbar muscles and ligaments (see Figure 8). Many popular exer- cises involve poor body mechanics and should be viewed with caution. Poor postures (e.g., sleeping on a soft mattress

or slouching in a chair) can also cause back strain (see Figure 9). Descriptions and examples of unsafe exercises and postures are provided later in the concept. VIDEO 2

cor22568_ch11_225-264.indd 237 14/09/12 6:42 PM

F O S T E R , C E D R I C 1 6 9 2 T S

238 Section 4 ▶ Physical Activity: Special Considerations

Exercise Guidelines for Back Health Some exercises and movements may put the back

and neck at risk. The human body is designed for motion. Nevertheless, certain movements can put the joints and mus- culoskeletal system at risk and should therefore be avoided. With respect to care of the spine, many contraindicated movements involve the extremes of hyperflexion and hyperextension. Hyperflexion causes increased pressure in the discs, potentially leading to disc herniation. Hyperexten- sion causes compressive wear and tear on the facet joints that join vertebral segments (see Figure 10 ). Hyperextension of the spine also causes narrowing of the intervertebral canal, potentially causing nerve impingement. Extremes of motion can be harmful to other joints as well. For example, knee hyperextension places excessive stress on structures at the back of the knee, whereas hyperflexion increases compressive forces under the kneecap (patello-femoral joint).

Following established exercise guidelines is

important for safe exercise. “Safe” exercises are defined as those performed with normal body posture, mechanics, and movement in mind. They don’t compromise the integrity or stability of one body part to the detriment of another. “Questionable” exercises, on the other hand, are exercises that may violate normal body mechanics and place the joints, ligaments, or muscles at risk for injury. No harm may occur from doing the exercise once, but repeated use over time can lead to injury. A number of commonly used exercises are regarded as poor choices (contraindicated) for nearly everyone in the general population due to the reasonable risk for injury over time. A separate category of questionable exercises are poor choices for certain segments of the population because of a specific health issue or known physical problem.

Differentiating exercises as “safe” or “questionable” can be difficult—even experts in the field have different opinions on the subject. These views change over time as new knowledge and research findings reshape our under- standing of the effect of exercise on the human body.

When considering the merits and risks of different

exercises, it may be necessary to consult an expert.

Professionals such as athletic trainers, biomechanists, phys- ical educators, physical therapists, and certified strength and conditioning specialists typically have college degrees and 4 to 8 years of study in such courses as anatomy, physiology, kinesiology, preventive and therapeutic exer- cise, and physiology of exercise. On-the-job training, a good physique or figure, and good athletic or dancing abil- ity are not sufficient qualifications for teaching or advising about exercise. Most fitness centers hire instructors and personal trainers with appropriate certifications. Unfor- tunately, certification is not always a requirement. When

searching for advice on training or exercise, inquire about an individual’s qualifications.

Exercises prescribed for a particular individual

differ from those that are good for everyone (mass

prescription). In a clinical setting, a therapist works with one patient. A case history is taken and tests made to determine which muscles are weak or strong, short or long. Exercises are then prescribed for that person. For example, a wrestler with a recent history of shoulder dislocation would probably be prescribed specific shoulder-strengthening exercises to regain stability in the joint. Common shoulder stretching exercises would likely be contraindicated for this individual. In this case, the muscles and joint capsule on the front of the shoulder are already quite lax to have allowed dislocation to occur in the first place.

Exercises prescribed or performed as a group cannot typically take individual needs into account. For exam- ple, when a physical educator, an aerobics instructor, or a coach leads a group of people in exercise, there is little (if any) consideration for individual differences, except for some allowance made in the number of repetitions or in the amount of weight or resistance used. Some of the exer- cises performed in this type of group setting may not be

Figure 10 ▶ Risks of hyperflexion and hyperextension.

Risks of hyperextension movements

Risks of hyperflexion movements

Wear and tear

Bulge

VIDEO 3

cor22568_ch11_225-264.indd 238 17/08/12 9:30 PM

F O S T E R , C E D R I C 1 6 9 2 T S

Concept 11 ▶ Body Mechanics: Posture, Questionable Exercises, and Care of the Back and Neck 239

appropriate for all individuals. Similarly, an exercise that is appropriate for a certain individual may not be appropriate for all members of a group. Since it is not always practical to prescribe individual exercise routines for everyone, it is often necessary to provide general recommendations that are appropriate for most individuals. The classification of exercises in this concept should be viewed in this context.

The risks associated with physical activity can be

reduced by modifying the variables or conditions

under which the activity is performed. While some exercises are contraindicated, it is almost always possible to find safer (or modified) alternatives. The variables that are typically under the direct control of the participant include exercise frequency (the number of repetitions per- formed in a given time span), duration (the length of time activity is sustained), intensity (the amount of resistance), speed (the velocity of activity, or rate, at which resistance is applied), and quality (the posture and mechanics of the body parts involved in the movement). Table 2 highlights these five activity variables, illustrates how each might be involved in potential injury, and provides suggestions for

modifying the variable to reduce the risk for injury. In some cases, changing a single variable may significantly reduce risk, but in other cases, multiple factors may need to be changed. In many cases, the best strategy is to look for a safer exercise. A variety of contraindicated exercises and safer alternatives are presented in Table 3 (pages 242–248) at the end of the concept.

Risks from exercise can’t be completely avoided. Vari- ables that are not always under the direct control of the participant include environmental conditions, such as temperature, humidity, or exercise surface. Likewise, the demands of sport and certain occupations may require individuals to train or work to the maximal limit of these variables (up to or just short of injury). Circumstances may not always permit every variable to be modified to suit an individual. However, making an active effort to adjust variables that are modifiable will make a difference in reducing injury risk.

Variables Activity Examples Potential Injury Modifications to Reduce Risk

Frequency • Repeated back hyperextension in a gymnast

• Repeated wrist movement in an assembly-line worker

Microtrauma to the joints undergoing repeated motions

• Maintain a balance of flexibility and strength in the vulnerable regions of the body.

• Provide rest/rotate workstations. • Use ergonomic modifications to the

worksite.

Duration • Sustained position of a deep squat in a baseball catcher

• Forward head posture of an office worker

Stress and strain to the muscles and ligaments used to hold the posture

• Strengthen the muscles of the knees and maintain leg muscle flexibility in the catcher.

• Take regular posture breaks in the office worker and modify computer station for good seated posture.

Intensity Excessive loads and reaction forces experienced by a • Power lifter • Runner • Construction worker

Stress and strain to the musculoskeletal system, especially the weaker portions of the back and shoulders

• Do a proper warm-up and correct training progression.

• Wear supportive shoes and clothing. • Be aware of personal limits, seeking

help or a spot when needed.

Speed High-velocity movement of • A 50-yd sprinter • The rapid fingering of a concert

pianist

• Motions applied over a short time under conditions of high tension predispose the muscles and tendons to injury.

• With fast-paced motions, precision is often sacrificed (particularly with fatigue), possibly leading to faulty movement patterns.

• Follow activity-specific training proto- cols to optimize recruitment of appro- priate muscle fiber types.

• Maintain balance of flexibility and strength.

• Use deep muscles for stability and superficial muscles for mobility.

Movement quality

• Extended range of motion dur- ing ballistic shoulder stretching of swimmers

• Poor body mechanics when shoveling snow

• Movement through extreme ranges or at the limit of normal motion can lead to instability or wear/tear of joints.

• Poor balance of forces throughout the body increases risk for stress and strain.

• Balance flexibility with strength and respect pain, the body’s signal of injury.

• Use good posture and body mechan- ics in recreational and lifestyle activi- ties to balance forces.

Table 2 ▶ Controllable Variables in Reducing Risk for Injury

Contraindicated Not recommended because of the potential for harm.

cor22568_ch11_225-264.indd 239 17/08/12 9:30 PM

F O S T E R , C E D R I C 1 6 9 2 T S

240 Section 4 ▶ Physical Activity: Special Considerations

Strategies for Action

An important step in taking action is

assessing your current status. The Healthy Back Tests consist of eight pass or fail items that will give you an idea of the areas in which you might need improvement. The Healthy Back Tests are described in Lab Resource Materials. You will take these tests in Lab 11A. Experts have identified behav- iors associated with potential future back and neck problems. A questionnaire is also provided for assessing these risk factors.

Adopting and maintaining good posture promotes good

back health. Lab 11B includes a posture test to help you evaluate your posture. Identify possible postural problems and take appropriate corrective action to reduce stress and strain on your back and neck.

Specific exercises are sometimes needed to prevent or help

rehabilitate postural, neck, and back problems. Exercises included in previous concepts were presented with health- related fitness in mind. The exercises included in this concept are not so different. They are either flexibility or strength/muscle endurance exercises for specific muscle groups; however,

each is selected specifically to help correct a postural problem or to remove the cause of neck and back pain. To that extent, these exercises may be classified as therapeutic. The same exercises may be called preventive because they can be used to prevent postural or spine problems. People who have back and neck pain should seek the advice of a physician to make certain that it is safe for them to perform the exercises.

The exercises in Tables 4 to 10 are not necessarily intended for all people. Rather, use your results on the Healthy Back Tests and the posture test to determine the exercises that are most appropriate for you. Table 3 (pages 242–248) provides information on “Questionable Exercises and Safe Alternatives.”

To facilitate the use of these exercises for back or postural problems, the most effective exercises for various maladies are organized in Tables 4 to 10. Lab 11C is designed to help you choose specific exercises related to test items in Lab 11A.

Keep records of progress to maintain a back care

program. Lab 11C provides an activity logging sheet for keeping records of your progress as you regularly perform exercises to build and maintain good back and neck fitness.

ACTIVITY

Clinical Applications (and Implications) of New Gaming Technology Gaming technology has spawned a variety of sport and clinical applications since it creates

an engaging and motivational climate for medical rehabilita- tion. Many physical therapy clinics now use the Wii to promote interest and motivation in patients. The games can be set up to require similar postures and body movements needed for traditional therapy exercises. Patients may tire of repetitive exercise but become engrossed in the task of the game and

forget that they are exercising. The potential of the tools for rehabilitation is clearly a positive application but new stud- ies report some clinical problems associated with excessive gaming—prompting some to characterize new conditions of Wii-itis and Nintendin-itis.

Do you see more advantages or disadvantages associated with the

increased availability of gaming technology in society?

CC G s

ACTIVITY

In the News

Some additional general guidelines will help

prevent postural, back, and neck problems. In addition to the suggestions for improving body mechanics noted in the previous sections, the following guidelines should be helpful:

• Do exercises to strengthen abdominal and hip exten- sors and to stretch the hip flexors and lumbar muscles if they are tight (see Tables 3 to 10 ).

• Avoid hazardous exercises. • Do regular physical activity for the entire body, such

as walking, jogging, swimming, and bicycling. • Choose an appropriate warm-up before strenuous activity. • Sleep on a moderately firm mattress or place a

3/4-inch-thick plywood board under the mattress.

• Avoid sudden, jerky back movements, especially twisting.

• Maintain a healthy weight. The smaller the waistline, the less the strain on the lower back.

• Use appropriate back and seat supports when sitting for long periods.

• Maintain good posture when carrying heavy loads; do not lean forward, sideways, or backward.

• Adjust sports equipment to permit good posture; for example, adjust a bicycle seat and handle bars to per- mit good body alignment.

• Avoid long periods of sitting at a desk or driving; take frequent breaks and adjust the car seat and headrest for maximum support.

cor22568_ch11_225-264.indd 240 17/08/12 9:30 PM

F O S T E R , C E D R I C 1 6 9 2 T S

Concept 11 ▶ Body Mechanics: Posture, Questionable Exercises, and Care of the Back and Neck 241

Web Resources American Physical Therapy Association www.apta.org American Spine Center www.americanback.com Back and Body Care www.backandbodycare.com Back Pain (Medline Plus-NIH) www.nlm.nih.gov/

medlineplus/backpain.html

Guide to Clinical Preventive Services www .thecommunityguide.org/about/guide.html

Low Back Pain (American Academy of Orthopaedic Surgeons) http://orthoinfo.aaos.org/topic .cfm?topic 5 A00311

Low Back Pain Fact Sheet (NIH) www.ninds.nih.gov/ disorders/backpain/detail_backpain.htm

MedX www.medxonline.com National Osteoporosis Foundation www.nof.org National Safety Council www.nsc.org National Strength and Conditioning Association

www.nsca-cc.org

Suggested Readings Bird, M., et al. 2011. The long-term benefits of a multi-

component exercise intervention to balance and mobility in healthy older adults. Archives of Gerontology and Geriatrics 52(2):211–216.

Brumitt, J. 2010. Core Assessment and Training. Champaign, IL: Human Kinetics.

Chang, Y., et al. 2010. Physical activity and cognition in older adults: The potential of Tai Chi Chuan. Journal of Aging and Physical Activity 18:451–472.

Ellingson, L. D., L. H. Colbert, and D. B. Cook. 2012. Physical activity is related to pain sensitivity in healthy women. Medicine and Science in Sports and Exercise 44(7):1401–1406.

Freburger, J. K., et al. 2009. The rising prevalence of chronic low back pain. Archives of Internal Medicine 169(3):251–258.

Jahnke, R., et al. 2010. A comprehensive review of health benefits of Qigong and Tai Chi. American Journal of Health Promotion 24(6):e1–e25.

Kiesel, K., Plisky, P., and R. Butler. 2011. Functional movement test scores improve following a standardized off-season intervention program in professional football players. Scandinavian Journal of Medicine and Science in Sports 21(2):287–292.

Martin, R. A., et al. 2008. Expenditures and health status among adults with back and neck problems. Journal of the American Medical Association 299(6):656–664.

Nelson, A., and J. Kokkonen. 2007. Stretching Anatomy. Champaign, IL: Human Kinetics.

O’Connor, F. G., et al. 2011. Functional movement screening: Predicting injuries in officer candidates. Medicine and Science in Sports and Exerc ise 43(12):2224–2230.

Rahman, S., et al. 2010. The association between obesity and low back pain: A meta-analysis. American Journal of Epidemi- ology 171(2):135–154.

Ratliff, J., A. Hilibrand, and A. R. Vaccaro. 2008. Spine-related expenditures and self-reported health status. Journal of the American Medical Association 299(22):2627.

Reid, Kieran F., and Roger A. Fielding. 2012. Skeletal muscle power: A critical determinant of physical functioning in older adults. Exercise & Sport Sciences 40(1):4–12.

Sanders, M. E. 2009. Off the floor exercises for back health. ACSM’s Health and Fitness Journal 13(6):33–35.

Sherman, K. J., et al. 2011. A randomized trial comparing yoga, stretching, and a self-care book for chronic low back pain. Archives of Internal Medicine 171(22):2019–2026.

Tilbrook, H. E., et al. 2011. Yoga for chronic low back pain: A randomized trial. Annals of Internal Medicine 155(9):569–578.

Healthy People

ACTIVITY

• Attain high-quality, longer lives free of preventable injury.

• Reduce activity limitations due to chronic back pain.

• Reduce joint pain in adults who have doctor-diagnosed arthritis.

• Reduce proportion of adults with arthritis limitations.

• Reduce prevalence of osteoporosis and hip fractures.

• Reduce sports and recreation injuries.

• Increase access to employee-based exercise facilities and programs.

A national goal is to increase the proportion of people who have

activity limitations due to chronic back pain and recreational injuries.

This concept provided information about the effects of questionable

exercises, poor posture, and poor body mechanics on back and neck

problems. It also described how functional fitness and core strength

can help promote better posture and improve functional fitness.

Do you think the overall prevalence of back and neck problems are

caused by a lack of awareness of good posture/body mechanics, poor

fitness, and core strength, or a combination?

cor22568_ch11_225-264.indd 241 10/09/12 7:23 PM

F O S T E R , C E D R I C 1 6 9 2 T S

242

Table 3 Questionable Exercises and Safer Alternatives

1. Questionable Exercise: The Swan

This exercise hyperextends the lower back and stretches the abdominals. The abdominals are too long and weak in most people and should not be lengthened further. Extension can be harmful to the back, potentially causing nerve impingement and facet joint compression. Other exercises in which this occurs include: cobras, backbends, straight-leg lifts, straight-leg sit-ups, prone- back lifts, donkey kicks, fire hydrants, backward trunk circling, weight lifting with the back arched, and landing from a jump with the back arched.

2. Questionable Exercise: Back-Arching Abdominal Stretch

This exercise can stretch the hip flexors, quadriceps, and shoulder flexors (such as the pectorals), but it also stretches the abdominals, which is not desired. Because of the armpull, it can potentially hyperflex the knee joint and strain neck musculature.

Safer Alternative Exercise: Back Extension

Lie prone over a roll of blankets or pillows and extend the back to a neutral or horizontal position.

Safer Alternative Exercise: Wand Exercise

This exercise stretches the front of the shoulders and chest. Sit with wand grasped at ends. Raise wand over- head. Be certain that the head does not slide forward. Keep the chin tucked and neck straight. Bring wand down behind shoulder blades. Keep spine erect. Hold. Press forward on the wand simultaneously by pushing with the hands. Relax; then try to move the hands lower, sliding the

wand down the back. Hold again. Hands may be

moved closer together to increase stretch on

chest muscles. If this is an easy exercise for you, try straightening the elbows and bringing the wand to waist level in back of you.

T a

b le

Note: All safer alternative exercises should be held 15 to 30 seconds unless otherwise indicated.

Deltoid

Erector spinae

Gluteus maximus

Hamstring

Pectoralis major

Pectoralis minor

cor22568_ch11_225-264.indd 242 17/08/12 9:30 PM

F O S T E R , C E D R I C 1 6 9 2 T S

243

3. Questionable Exercise: Seated Forward Arm Circles with Palms Down

This exercise (arms straight out to the sides) may cause pinching of the rotator cuff and biceps tendons between the bony structures of the shoulder joint and/or irritate the bursa in the shoulder. The tendency is to emphasize the use of the stronger chest muscles (pectorals) to perform the motion rather than emphasizing the weaker upper back muscles.

Safer Alternative Exercise: Seated

Backward Arm Circles with Palms Up

Sit, turn palms up, pull in chin, and contract abdominals. Circle arms backward.

4. Questionable Exercise: Double-Leg Lift

This exercise is usually used with the intent of strength- ening the abdominals, when in fact it is primarily a hip flexor (iliopsoas) strengthening exercise. Most people have overdeveloped the hip flexors and do not need to further strengthen those muscles because this may cause forward pelvic tilt. Even if the abdominals are strong enough to contract isometrically to prevent hyperextension of the lower back, the exercise produces excess stress on the discs.

Safer Alternative Exercise: Reverse Curl

This exercise strengthens the lower abdominals. Lie on your back on the floor and bring your knees in toward the chest. Place the arms at the sides for support. For movement, pull the knees toward the head, raising the hips off the floor. Do not let knees go past the shoulders. Return to starting position and repeat.

T a

b le

Questionable Exercises and Safer Alternatives Table 3

Rectus abdominis

Deltoid

cor22568_ch11_225-264.indd 243 17/08/12 9:30 PM

F O S T E R , C E D R I C 1 6 9 2 T S

244

Table 3 Questionable Exercises and Safer Alternatives

5. Questionable Exercise: The Windmill

This exercise involves simultaneous rotation and flexion (or extension) of the lower back, which is contraindi- cated. Because of the orientation of the facet joints in the lumbar spine, these movements violate normal joint mechanics, placing tremen- dous torsional stress on the joint capsule and discs.

6. Questionable Exercise: Neck Circling

This exercise and other exercises that require neck hyperextension (e.g., neck bridging) can pinch arter- ies and nerves in the neck and at the base of the skull, cause wear and tear to small joints of the spine, and

produce dizziness or myofascial trigger points. In people with

degenerated discs, it can cause dizziness, numb- ness, or even precipitate strokes. It also aggra- vates arthritis and degenerated discs.

Safer Alternative Exercise:

Back-Saver Toe Touch

Sit on the floor. Extend leg and bend the other knee, plac- ing the foot flat on the floor. Bend at the hips and reach forward with both hands. Grasp one foot, ankle, or calf depending upon the distance you can reach. Pull forward with your arms and bend forward. Slight bend in the knee is acceptable. Hold. Repeat with the opposite leg.

Safer Alternative Exercise: Head Clock

This exercise relaxes the muscle of the neck. Assume a good posture (seated with legs crossed or in a chair), and imagine that your neck is a clock face with the chin at the center. Flex the neck

and point the chin at 6:00, hold, lift the chin; repeat pointing chin to 4:00, to 8:00, to 3:00 and finally to 9:00. Return to center position with

chin up after each movement.

T a

b le

Erector spinae

Adductors

Gluteals

Sternocleidomastoid

Splenius capitis

Semispinalis capitis

Levator scapulae

Trapezius Scalenes

cor22568_ch11_225-264.indd 244 17/08/12 9:30 PM

F O S T E R , C E D R I C 1 6 9 2 T S

245

7. Questionable Exercise: Shoulder Stand Bicycle

This exercise and the yoga positions called the plough and the plough shear (not shown) force the neck and upper back to hyperflex. It has been estimated that 80 percent of the population has forward head and kyphosis (humpback) with accompanying weak muscles. This exercise is especially dangerous for these people. Neck hyperflex- ion results in excessive stretch on the ligaments and nerves. It can also aggravate preexisting arthritic conditions. If the purpose for these exercises is to reduce gravitational effects on the circulatory system or internal organs, lie on a tilt board with the feet elevated. If the purpose is to warm up the muscles in the legs, slow jog in place. If the purpose is to stretch the lower back, try the leg hug exercise.

Safer Alternative Exercise: Leg Hug

Lie on your back with the knees bent at about 90 degrees. Bring your knees to the chest and wrap the arms around the back of the thighs. Pull knees to chest and hold.

8. Questionable Exercise: Straight-Leg and Bent-Knee Sit-Ups

There are several valid criticisms of the sit-up exercise. Straight-leg sit-ups can displace the fifth lumbar vertebra, causing back problems. A bent-knee sit-up creates less shearing force on the spine, but some recent studies have shown it produces greater compression on the lumbar

discs than the straight-leg sit-up. Placing the hands

behind the neck or head during the sit-up or during a crunch results in hyperflexion of the neck.

Safer Alternative Exercise: Crunch

Lie on your back with the knees bent more than 90 degrees. Curl up until the shoulder blades lift off the floor, then roll down to starting position and repeat. There are sev- eral safe arm positions. The easiest is with the arms extended straight in front of the body. Alternatives are with the arms

crossed over the chest or the palms or fist held beside

the ears.

T a

b le

Questionable Exercises and Safer Alternatives Table 3

Erector spinae

Gluteals

Rectus abdominis

cor22568_ch11_225-264.indd 245 17/08/12 9:31 PM

F O S T E R , C E D R I C 1 6 9 2 T S

246

Table 3 Questionable Exercises and Safer Alternatives

9. Questionable Exercise: Standing Toe Touches or Double-Leg Toe Touches

These exercises—especially when done ballistically—can produce degenerative changes at the vertebrae of the lower back. They also stretch the ligaments and joint capsule of the knee. Bending the back while the legs are straight may cause back strain, particularly if the movement is done bal- listically. If performed only on rare occasions as a test, the chance of injury is less than if incorporated into a regular exercise program. Safer stretches of the lower back include the leg hug, the single knee-to- chest, the back-saver hamstring stretch, and the back-saver toe touch.

Safer Alternative Exercise:

Back-Saver Hamstring Stretch

This exercise stretches the hamstring and lower back muscles. Sit with one leg extended and one knee bent, foot turned outward and close to the buttocks. Clasp hands behind back. Bend forward from the hips, keep- ing the low back as straight as possible. Allow bent knee to move laterally so trunk can move forward. Stretch and hold. Repeat with the other leg.

Safer Alternative Exercise:

One-Leg Stretch

This exercise stretches the hamstring muscles. Stand with one foot on a bench, keeping both legs straight. Hinge forward from the hips keeping shoulders back and chest up. Bend forward until a pull is felt on the back side of the thigh. Hold. Repeat.

T a

b le

10. Questionable Exercise: Bar Stretch

This type of stretch may be harmful. Some experts have found that when the extended leg is raised 90 degrees or more and the trunk is bent over the leg, it may lead to

sciatica and piriformis syndrome, especially in the per-

son who has lim- ited flexibility.

Hamstring

cor22568_ch11_225-264.indd 246 17/08/12 9:31 PM

F O S T E R , C E D R I C 1 6 9 2 T S

247

11. Questionable Exercise: Shin and Quadriceps Stretch

This exercise causes hyperflexion of the knee. When the knee is hyperflexed more than 120 degrees and/or rotated outward by an external t orque, the liga- ments and joint capsule are stretched, and damage to the cartilage may occur. Note: one of the quadriceps, the rectus femoris, is not stretched if the trunk is allowed to bend forward because it crosses the hip as well as the knee joint. If the exercise is used to stretch the quadriceps, substitute the hip and thigh stretch. For most people it is not neces- sary to stretch the shin muscles, since they are often elongated and weak; however, if you need to stretch the shin muscles to relieve muscle soreness, try the shin stretch.

Safer Alternative Exercise:

Hip and Thigh Stretch

Kneel so that the front leg is bent at 90 degrees (front knee directly above the front ankle). The knee of the back leg should touch the floor well behind the front

foot. Press the pelvis for- ward and downward. Hold. Repeat with the opposite leg forward. Do not bend the front knee more than 90 degrees.

Safer Alternative Exercise: Shin Stretch

Kneel on your knees, turn to right and press down on right ankle with right

hand. Hold. Keep hips thrust for- ward to avoid hyperflexing the

knees. Do not sit on the heels. Repeat on the left side.

T a

b le

Questionable Exercises and Safer Alternatives Table 3

Quadriceps

Tibialis anterior

Extensor hallucis longus

Extensor digitorum longus

12. Questionable Exercise: The Hero

Like the shin and quadriceps stretch, this exercise causes hyperflexion of the knee. It also causes torque on the hyperflexed knee. For these reasons the liga- ments and joint capsule are stretched and the cartilage may be damaged. For most people it is not necessary to stretch the shin muscles since they are often elon- gated and weak; however, if you need to stretch the shin muscles, use the shin stretch. If this exercise is used to stretch the quadriceps, substitute the hip and thigh stretch.

Sciatica Pain along the sciatic nerve in the buttock and leg. Piriformis Syndrome Muscle spasm and nerve entrapment in the pyriformis muscle of the buttocks region, causing pain in the buttock and referred pain down the leg (sciatica). Torque A twisting or rotating force.

cor22568_ch11_225-264.indd 247 17/08/12 9:31 PM

F O S T E R , C E D R I C 1 6 9 2 T S

248

Table 3 Questionable Exercises and Safer Alternatives

13. Questionable Exercise: Deep Squatting Exercises

This exercise, with or without weights, places the knee joint in hyperflexion, tends to “wedge it open,” stretching the ligaments, irritating the synovial membrane, and pos- sibly damaging the cartilage. The joint has even greater stress when the lower leg and foot are not in straight alignment with the knee. If you are performing squats to strengthen the knee and hip extensors, try substitut- ing the alternate leg kneel or half-squat with free weight or leg presses on a resistance machine.

14. Questionable Exercise: Knee Pull-Down

This exercise can result in hyperflexion of the knee. The arms or hands placed on top of the shin places undue stress on the knee joint.

Safer Alternative Exercise: Half Squat

This exercise develops the muscles of the thighs and buttocks. Stand upright with feet shoulder width apart.

Squat slowly by moving hips back- wards, then bending knees.

Keep shins vertical. Bend knees 45–90 degrees. Repeat.

Safer Alternative Exercise:

Single Knee-to-Chest

Lie down with both knees bent, draw one knee to the chest by pulling on the thigh with the hands, then extend the knee and point the foot toward the ceiling. Hold. Pull to chest again and return to starting position. Repeat with other leg.

T a

b le

Quadriceps

Gluteus maximus

Hamstring

cor22568_ch11_225-264.indd 248 17/08/12 9:31 PM

F O S T E R , C E D R I C 1 6 9 2 T S

249

T a

b le

1. Back-Saver Hamstring Stretch

This exercise stretches the hamstrings and calf muscles. Sit on the floor with the feet against the wall or an immovable object. Bend left knee and bring foot close to buttocks. Clasp hands behind back. Bend forward from hips, keeping lower back as straight as possible.

Let bent knee rotate outward so trunk can move forward keeping back flat. Hold and repeat on each leg.

3. Hip and Low Back Stretch

This exercise stretches the hip flexors of one leg and the gluteals and lumbar muscles of the oppo- site leg. Lie on your back. Draw one knee up to the chest and pull thigh toward chest with the hands; then slowly return to the original posi- tion. Repeat with other knee. Do not grasp knee— grasp thigh. If a partner or a weight stabilizes the extended leg, the hip flexor muscles on that leg will be stretched.

2. Single Knee-to-Chest

This exercise stretches the lower back, gluteals, and hamstring muscles. Lie on your back with knees bent. Use hands on back of thigh to draw one knee to the chest. Hold. Then extend the knee and point the foot

toward the ceiling. Hold. Return to the starting posi- tion without arching your back. Repeat with other leg.

4. Hip and Thigh Stretch

This exercise stretches the hip flexor muscles and helps prevent or correct forward pelvic tilt, lumbar lordosis, and backache. Place right knee directly above right ankle and stretch left leg backward so knee touches floor. If neces- sary, place hands on floor for balance. Press pelvis forward and downward. Hold. Repeat on opposite side. Cau- tion: Do not bend front knee more than 90 degrees.

Hamstrings

Gastrocnemius Gluteus maximus

Gluteus maximus

Lower back

Hamstrings

Iliopsoas

Rectus femoris

Stretching Exercises for the Hip Flexors and Hamstrings Table 4

When performed on a regular basis, these exercises will help maintain neutral spine posture and improve the flexibility of the hip flexor and hip extensor musculature. (Tightness of these muscles can, respectively, contribute to a forward or backward pelvic tilt due to their attachments to the pelvis.) Hold stretches for 15 to 30 seconds.

VIDEO 4

Iliopsoas

Rectus femoris

cor22568_ch11_225-264.indd 249 17/08/12 9:31 PM

F O S T E R , C E D R I C 1 6 9 2 T S

250

T a

b le

Table 5 Core Stabilization Exercises These exercises help train the abdominal and buttock muscles to provide postural stability by maintaining the pelvis in a neutral position during activity. They help prevent or correct lumbar lordosis, abdominal ptosis (see Table 1), and backache. Hold exercises for 15 to 30 seconds.

1. Abdominal Hollowing on Hands

and Knees

Begin on hands and knees with lower back in a neutral position, stomach muscles relaxed and sag- ging and eyes looking at the floor. Hands should be aligned directly below shoulders and knees directly below hips. The action is to pull the belly button “in and up,” drawing it toward the spine. If performed correctly, the muscles below the umbilicus will flatten, rather than bulge. Recruitment of the transverse abdominus may be facilitated by coughing and then holding the muscle con- traction. The exercise is held for 10–30 seconds. Breathe normally throughout the contraction. Repeat 10 times.

3. Horizontal Side Support

Begin in side lying position with the body resting on the forearm. Slowly lift the pelvis until the body forms a straight line from foot to shoulder. Hold 10–30 seconds. Repeat 8–12 times.

4. Head Nod

Lie flat on the back without a pillow. Gently nod the head in a “yes” motion. Motion should result in the tightening of muscles deep in the front of the neck. Place two fin- gers over the sides of the neck to monitor for the unde- sirable substitution of stronger muscles in this region.

Hold 10–30 seconds (or as long as can be maintained without substitution). Repeat 10 times. Progress this exercise by first nod- ding “yes” and then lift- ing the head ¼ inch to ½ inch off the surface.

2. Abdominal Hollowing in Wall Support

Begin standing with feet 6 inches from the wall and back gently resting against the surface. Maintain a neutral spine. Contract the muscles below the belly button by pulling the abdominal wall “in and up.” The pelvic floor may be contracted at the same time by pull- ing it “up and in” in a gripping motion. Breathe throughout the contraction. Hold 10–30 seconds. Repeat 10 times.

Internal abdominal oblique (cut)

Transverse abdominal (cut)

Multifidus Quadratus lumborum

Deep neck flexors

Internal abdominal oblique (cut) Transverse abdominal (cut)

cor22568_ch11_225-264.indd 250 17/08/12 9:31 PM

F O S T E R , C E D R I C 1 6 9 2 T S

251

T a

b le

Exercises for Muscle Fitness of the Abdominals Table 6 These exercises are designed to increase the strength of the abdominal muscles. Strong abdominal muscles are important for maintaining a neutral pelvis, maintaining good posture, and preventing backache associated with lordosis.

1. Reverse Curl

Lie on your back. Bend the knees and bring knees in toward the chest. Place arms at sides for balance and sup- port. Pull the knees toward the chest, raising the hips off the floor. Do not let the knees go past the shoulders. Return to the starting position. Repeat.

2. Crunch (Curl-Up)

Lie on your back with your knees bent and palms on ears. If desired, legs may rest on bench to increase dif- ficulty. For less resistance, place hands at side of body. For more resistance, move hands higher. Curl up until shoulder blades leave floor, then roll down to the start-

ing position. Repeat. Variation: extend the arms or cross

the arms over your chest.

3. Crunch with Twist (on Bench)

Lie on your back with your feet on a bench, knees bent at 90 degrees. Arms may be extended or on shoulders or hands on ears (the most difficult). Same as crunch except twist the upper trunk so the right shoulder is higher than the left. Reach toward the left knee with the right elbow. Hold. Return and repeat to the opposite side. (This exer- cise is not recommended for people with lower back pain due to the combined motions of flexion and rotation.)

4. Sitting Tucks

Sit on floor with feet raised, arms extended for balance. Alternately bend and extend legs without letting your back or feet touch floor. (This is an advanced exercise and is not recom- mended for people who have back pain.)

Rectus abdominis External obliques

External abdominal oblique (cut)

Internal abdominal oblique

Rectus abdominis

VIDEO 5

cor22568_ch11_225-264.indd 251 17/08/12 9:31 PM

F O S T E R , C E D R I C 1 6 9 2 T S

252

T a

b le

Table 7 Stretching and Strengthening Exercises for the Muscles of the Neck

These exercises are designed to increase strength in the neck muscles and to improve neck range of motion. They are helpful in preventing and resolving symptoms of neck pain and for relieving trigger points. Hold stretches for 15–30 seconds.

1. Neck Rotation Exercise

This PNF exercise strengthens and stretches the neck rotators. It should always be done with the head and neck in axial extension (good alignment). It is particularly useful for relieving trigger point pain and stiffness. Place palm of left hand against left cheek. Point fingers toward ear and point elbow forward. Turn head and neck to the left; contract while gently resist- ing with left hand. Contract neck mus- cle for 6 seconds. Relax and turn head to right as far as possible; hold stretch. Repeat four times; repeat on opposite side.

2. Isometric Neck Exercises

This exercise strengthens the neck muscles. Sit and place one or

both hands on the head as shown. Assume good head and neck posture by tucking the chin, flat- tening the neck, and pushing the crown of the head up (axial extension). Apply resistance (a) side-

ward, (b) backward, and (c) forward. Contract the neck muscles to prevent the head and neck from moving. Hold contraction for 6 sec- onds. Repeat each exercise up to six times. Note: for neck muscles,

it is probably best to use a little less than a maximal contraction, espe-

cially in the presence of arthritis, degen- erated discs, or injury.

3. Chin Tuck

This exercise stretches the mus- cles at the base of the skull and reduces headache symptoms. Place hands together at the base of the head. Tuck in the chin and gently press head backward into your hands, while looking straight ahead. Hold.

4. Upper Trapezius Stretch

This exercise stretches the upper trapezius muscle and relieves neck pain and headache. To stretch the right upper trapezius, place left hand on top of head, right hand behind back. Gently turn head toward left under-

arm and tilt chin toward chest. Increase stretch by gently

drawing head forward with left hand. Hold. Repeat to opposite side.

Trapezius Sternocleidomastoid

Neck rotator and extensors

Neck flexors

Trapezius

Deep extensors

VIDEO 6

cor22568_ch11_225-264.indd 252 17/08/12 9:31 PM

F O S T E R , C E D R I C 1 6 9 2 T S

253

T a

b le

Exercises for Trunk Mobility Table 8 These exercises are designed to increase the strength and mobility of the muscles that move the trunk. They are espe- cially helpful for people with chronic back pain. Hold stretches for 15 to 30 seconds.

1. Upper Trunk Lift

Lie on a table, bench, or special-purpose bench designed for trunk lifts with the upper half of the body hanging over the edge. Have a partner sta- bilize the feet and legs while the trunk is raised par- allel to the floor; then lower the trunk to the starting posi- tion. Lift smoothly, one seg- ment of the back at a time. Place hands behind neck or on ears. Do not raise past the horizontal or arch the back or neck.

2. Trunk Lift

This exercise develops the muscles of the upper back and corrects round shoulders. Lie face down with hands clasped behind the neck. Pull the shoulder blades together, raising the elbows off the floor. Slowly raise the head and chest off the floor by arching the upper back. Return to the starting position. Repeat. For less resis- tance, hands may be placed under thighs. Caution: Do not arch the lower back or neck. Lift only until the ster-

num (breastbone) clears the floor. Varia- tions: arms down at sides (easiest), hands by head, hands extended (hardest).

3. Side Bend

This exercise stretches the trunk lateral flexors. Stand with feet shoulder- width apart. Stretch left arm overhead to right. Bend to right at waist, reach- ing as far to right as possible with left arm; reach as far as possible to the left with right arm. Hold. Do not let trunk rotate or lower back arch. Repeat on opposite side. Note: this exercise is more effective if a weight is held down at the side in the hand opposite the side being stretched. More stretch will occur if the hip on the stretched side is dropped and most of the weight is borne by the opposite foot.

4. Supine Trunk Twist

This exercise increases the flexibility of the spine and stretches the rotator muscles. Lie on your back with your arms extended at shoulder level. Place left foot on right knee cap. Twist the lower

body by lowering left knee to touch floor on right. Turn head to left. Keep shoulders and arms on floor. Hold.

Back extensors

Trunk Lateral Flexors

Trunk rotators

Trunk extensors

VIDEO 7

cor22568_ch11_225-264.indd 253 17/08/12 9:31 PM

F O S T E R , C E D R I C 1 6 9 2 T S

254

T a

b le

6. Press-Up (McKenzie Extension Exercise)

This exercise increases flexibility of the lumbar spine and restores normal lordotic curve, especially for people with a flat lumbar spine. Lie on your stomach with hands under the face. Slowly press up to a rest position on forearms. Keep pelvis on floor. Relax and hold 10 sec- onds. Perform 5–10 repetitions. Do several times a day. Progress to gradually straightening the elbows while keeping the pubic bone on the floor. Caution: do not perform if you have lordosis or if you feel any pain or discomfort in the back or legs. Note: a prone press-up will feel good as a stretch after doing abdominal strength or endurance exercises. This relaxed lordotic position can be performed while standing. Place the hands in the small of the back and gently arch the back and hold. This should feel good after sitting for a long period with the back flat.

5. Lower Trunk Lift

This exercise devel- ops low back and hip strength. Lie on your stomach on a bench or table with legs hang- ing over the edge. Have a partner stabilize the upper back or grasp the edges of the table with hands. Raise the legs parallel to the floor and lower them. Do not raise past the horizontal or arch the back. Suggested progres- sion: (1) Begin by alternating legs; (2) when you can do 25 reps, add ankle weights; (3) when you can do 25 reps, lift both legs simulta- neously (no weights).

Table 8 Exercises for Trunk Mobility

Gluteus maximus

Erector spinae

cor22568_ch11_225-264.indd 254 17/08/12 9:31 PM

F O S T E R , C E D R I C 1 6 9 2 T S

255

T a

b le

Stretching and Strengthening Exercises for Round Shoulders

Table 9

These exercises are designed to stretch the muscles of the chest and strengthen the muscles that keep the shoulders pulled back in good alignment (scapular adduction).

1. Arm Lift

This exercise strengthens the scapular adductors. Lie on stomach with arms in reverse-T. Rest forehead on floor.

Maintain the arm position and contract the muscles between the shoulder blades, lifting the arms as high as possible

without raising head and trunk. Hold. Relax and repeat. Note: if the arms are first pressed against

the floor before lift- ing, this becomes a PNF exercise and range of motion may

be greater. Variation: this more advanced exercise is performed in the same way except the arms are extended overhead.

2. Seated Rowing

This exercise strengthens the scapular adductors (rhom- boid and trapezius). Sit facing pulley, feet braced and knees slightly bent. Grasp bar, palms down with hands shoulder-width apart. Pull bar to chest, keeping elbows high, and return.

3. Wand Exercise

This exercise stretches the muscles on the front of the shoulder joint. Sit with wand grasped at ends. Raise wand overhead. Be certain that the head does not slide forward into a “poke neck” position. Keep the chin tucked

and neck straight. Bring wand down behind shoulder

blades. Keep spine erect; hold.

Hands may be moved closer together to increase stretch on chest muscles.

4. Pectoral Stretch

This exercise stretches the chest muscle (pectorals).

1. Stand erect in doorway with arms raised 45 degrees, elbows bent, and hands grasping door jambs, feet in front stride position. Press out on door frame, contract- ing the arms maximally for 3 seconds. Relax and shift weight forward on legs. Lean into doorway, so muscles on front of shoulder joint and chest are stretched. Hold.

2. Repeat with arms raised 90 degrees.

3. Repeat with arms raised 135 degrees.

(This exercise is not recom- mended for people with shoul- der instability. Discontinue if it causes numbness in the arms or hands.)

Trapezius Rhomboids

Pectoralis major

Pectoralis minor

VIDEO 8

cor22568_ch11_225-264.indd 255 17/08/12 9:31 PM

F O S T E R , C E D R I C 1 6 9 2 T S

256

T a

b le

1 0

Table 10 Lumbar Stabilization Exercises with Stability Balls These exercises are designed to help improve the ability of the back to stabilize and support the trunk. The physioballs provide a useful way to learn to balance the body in these positions.

1. Balancing

Contract abdominal muscles. Straighten one knee and raise opposite arm over head. Alternate sides. To increase difficulty, position ball farther from your body. Variation: slowly walk ball forward or backward with legs. Be careful not to arch back.

2. Marching

Sit up straight with hips and knees bent 90 degrees. Con- tract abdominal muscles. Slowly raise one heel off the ground and opposite arm over head. Alternate sides. To increase difficulty, slowly raise one foot 2 inches from floor, alternating sides.

3. Wall Support

Stand against a wall with ball supporting low back. Contract abdominal muscles. Slowly bend knees 45 to 90 degrees and hold 5 seconds. Straighten knees and repeat. Raise both arms over head to increase difficulty.

4. Stomach Roll

Lie prone over ball with abdominal region supported. Lower back and neck should be in neutral position with hands supported on floor directly under shoulders. Raise one leg off the floor while maintaining balance and a neutral spine. Alternate sides. To increase difficulty, raise one leg and opposite arm.

90º 90º

cor22568_ch11_225-264.indd 256 17/08/12 9:31 PM

F O S T E R , C E D R I C 1 6 9 2 T S

L a

b R

e s o

u rc

M a

te ria

257

H e a lth

y B a c k Te

sts

Lab Resource Materials: Healthy Back Tests

Chart 1 Healthy Back Tests

Physicians and therapists use these tests, among others, to make differential diagnoses of back problems. You and your partner can use them to determine if you have muscle tightness that may put you at risk for back problems. Discontinue any of these tests if they produce pain, numbness, or tingling sensations in the back, hips, or legs. Experiencing any of these sensations may be an indication that you have a low back problem that requires diagnosis by your physician. Partners should use great caution in applying force. Be gentle and listen to your partner’s feedback.

FLEXIBILITY

Test 1—Straight-Leg Lift

Lie on your back with hands behind your neck. The partner on your left should stabilize your right leg by placing his or her right hand on your knee. With the left hand, your partner should grasp your left ankle and raise your left leg as near to a right angle as possible. In this position (as shown in the diagram), your lower back should be in contact with the floor. Your right leg should remain straight and on the floor throughout the test.

If your left leg bends at the knee, this indicates short hamstring muscles. If your back arches and/or your right leg does not remain flat on the floor this indicates short lumbar muscles or hip flexor muscles. To pass the test, each leg should be able to reach approximately 90 degress without the knee or back bending. (Both sides must pass in order to pass the test.)

Test 2—Thomas Test

Lie on your back on a table or bench with your right leg extended beyond the edge of the table (approximately one-third of your thigh off the table). Bring your left knee to your chest and pull your thigh down tightly with your hands. Lower your right leg. Your lower back should remain flat against the table, as shown in the diagram. To pass the test, your right thigh should be at table level or lower.

Test 3—Ober Test

Lie on your left side with your left leg flexed 90 degrees at the hip and 90 degrees at the knee. A partner should place your right hip in slight extension and right knee with just a slight bend (~20 degrees flexion). Your partner stabilizes your pelvis with the left hand to prevent movement. Your partner then allows the weight of the top leg to lower the leg to the floor. To pass the test your knee or upper leg should be able to touch the table.

CORE TRUNK ENDURANCE TESTS

Test 4—Leg Drop Test*

Lie on your back on a table or on the floor with both legs extended overhead. Flatten your low back against the table or floor by tightening your abdominals. Slowly lower your legs while keeping your back flat.

If your back arches before you reach a 45-degree angle, your abdominal muscles are too weak and you fail the test. A partner should be ready to support your legs if needed to prevent your lower back from arching or strain to the back muscles.

*The Leg Drop Test is suitable as a diagnostic test when performed one time. It is not a good exercise to be performed regularly by most people. If it

causes pain, stop the test.

45˚

cor22568_ch11_225-264.indd 257 17/08/12 9:31 PM

F O S T E R , C E D R I C 1 6 9 2 T S

258

L a

b R

e s o

u rc

M a

te ri

a ls Test 5—Isometric Abdominal Test. Lie supine with hips bent

45 degrees, feet flat on the floor and arms by the side. Draw a line 4 1/2 inches beyond fingertips. Tuck chin and curl trunk forward, touching line with fingers. To pass, hold for 30 seconds.

Test 6—Isometric Extensor Test. Lie on a table with upper half of the body hanging over the edge and arms crossed in front of chest. Have a partner stabilize your feet and legs. Raise your trunk smoothly until your back is in a horizontal position parallel to the floor. Do not arch the back. To pass the test hold this position for 30 seconds.

Test 7—Prone Bridge. Support yourself on the floor by resting on forearms and balls of feet, body extended and back straight. Elbows are placed directly underneath shoulders. Look straight down toward hands. Do not arch the back. To pass the test hold this position for 30 seconds.

Test 8—Quadruped Stabilization. Begin on hands and knees. Place hands directly below shoulders and knees directly below hips. Draw abdominals in. Extend one arm and opposite leg to a horizontal position. Do not allow back to arch or body to sway. To pass, hold position for 30 seconds.

Test 9—Right Lateral Bridge. Lie on your right side with legs extended. Raise pelvis off the floor until trunk is straight and body weight is supported on arm and feet. Do not roll forward or backward. Do not arch back. Hold this position for 30 seconds.

Test 10—Left Lateral Bridge. Lie on your left side with legs extended. Raise pelvis off the floor until trunk is straight and body weight is supported on arm and feet. Do not roll forward or backward or arch back. To pass the test, hold this position for 30 seconds.

Chart 1 Healthy Back Tests (Continued)

Classification Number of Tests Passed

Excellent 8–10

Very good 7

Good 6

Fair 5

Poor 1–4

Chart 2 Healthy Back Test Ratings

H e a lt h y

B a c k

Te st

cor22568_ch11_225-264.indd 258 17/08/12 9:31 PM

F O S T E R , C E D R I C 1 6 9 2 T S

259

T h e H

e a lth

y B a c k T

e sts a

n d

B a c k/N

e c k Q

u e stio

n n a ire

L a

b 1

1 A

Lab 11A The Healthy Back Tests and Back/Neck Questionnaire

Name Section Date

Purpose: To self-assess your potential for back problems using the Healthy Back Tests and the back/neck questionnaire

Procedures

1. Answer the questions in the following back/neck questionnaire. Count your points for nonmodifiable factors, modi- fiable factors, and total score, and record these scores in the Results section. Use Chart 1 to determine your rating for all three scores and record them in the Results section.

2. With a partner, administer the Healthy Back Tests to each other (see Lab Resource Materials). Determine your rat- ing using Chart 2. Record your score and rating in the Results section. If you did not pass a test, list the muscles you should develop to improve on that test.

3. Complete the Conclusions and Implications section.

Risk-Factor Questionnaire for Back and Neck Problems

Directions: Place an X in the appropriate circle after each question. Add the scores for each of the circles you checked to determine your modifi able risk, nonmodifi able risk, and total risk scores.

Nonmodifi able

1. Do you have a family history of osteoporosis, arthritis, 0 No 1 Yes rheumatism, or other joint disease?

2. What is your age? 0 <40 1 40–50 2 51–60 3 61+

3. Did you participate extensively in these sports when you were young: gymnastics, football, weight lifting, skiing, 0 No 1 Some 3 Extensive ballet, javelin, or shot put?

4. How many previous back or neck problems have you had? 0 None 1 1 2 2 5 3+

Modifi able

5. Does your daily routine involve heavy lifting? 0 No 1 Some 3 A lot

6. Does your daily routine require you to stand for long periods? 0 No 1 Some 3 A lot

7. Do you have a high level of job-related stress? 0 No 1 Some 3 A lot

8. Do you sit for long periods of time (computer operator, typist, 0 No 1 Some 3 A lot or similar job)?

9. Does your daily routine require doing repetitive movements or holding objects (e.g., baby, briefcase, sales suitcase) 0 No 1 Some 3 A lot for long periods of time?

10. Does your daily routine require you to stand or sit with poor posture (e.g., sitting in a low car seat, reaching 0 No 1 Some 3 A lot overhead with head tilted back)?

11. What is your score on the Healthy Back Tests? 0 6–7 1 5 3 4 5 0–3

12. What is your score on the posture test in Lab 11B? 0 0–2 1 3–4 3 5–7 5 8+

cor22568_ch11_225-264.indd 259 11/09/12 5:01 PM

F O S T E R , C E D R I C 1 6 9 2 T S

260

T h e H

e a lt h y

B a c k

T e st

s a n d

B a c k/

N e c k

Q u e st

io n n a ir e

L a

b 1

1 A

Results

Tests Pass Fail If you failed, what exercise should you do?

1. Straight-leg lift

2. Thomas test

3. Ober test

4. Leg drop test

5. Isometric abdominal test

6. Isometric extensor test

7. Prone bridge

8. Quadruped stabilization

9. Right lateral bridge

10. Left lateral bridge

Total

Back/Neck Questionnaire

Score Rating

Back Tests

Score Rating

Conclusions and Implications: In several sentences, discuss your need to do exercises for care of the back and neck. Include in your discussion whether you think your muscles are fi t enough to prevent problems, the areas in which you are most likely to experience problems, and steps you might take to prevent future problems. Use your test results to answer.

Rating Modifiable Score Nonmodifiable Score Total Score

Very high risk 7+ 12+ 19+

High risk 5–6 8–11 13–17

Average risk 3–4 4–7 7–11

Low risk 0–2 0–3 0–5

Chart 1 Back/Neck Questionnaire Ratings

Classification Number of Tests Passed

Excellent 8–10

Very good 7

Good 6

Fair 5

Poor 1–4

Chart 2 Healthy Back Tests Ratings

cor22568_ch11_225-264.indd 260 17/08/12 9:31 PM

F O S T E R , C E D R I C 1 6 9 2 T S

261

E va

lu a tin

g P

o stu

re L

a b

1 1 B

Lab 11B Evaluating Posture

Name Section Date

Purpose: To learn to recognize postural deviations and thus become more posture conscious and to determine your postural limitations in order to institute a preventive or corrective program

Procedures

1. Wear as little clothing as possible (bathing suits are recommended) and remove shoes and socks. 2. Work in groups of two or three, with one person acting as the subject while partners serve as examiners; then

alternate roles. a. Stand by a vertical plumb line. b. Using Chart 1 and Figure 1, check any deviations and indicate their severity using the following point scale

(0 = none, 1 = slight, 2 = moderate, and 3 = severe). c. Total the score and determine your posture rating from the Posture Rating Scale (Chart 2). 3. If time permits, perform back and posture exercises (see Lab 11C). 4. Complete the Conclusions and Implications section.

Results

Record your posture score:

Record your posture rating from the Posture Rating Scale in Chart 2:

Side View Points

Forward head

Rounded shoulders

Excessive lordosis (lumbar)

Abdominal ptosis

Hyperextended knees

Total scores

Classification Total Score

Excellent 0–3

Very good 4–6

Good 7–9

Fair 10–12

Poor 12 or more

Chart 2 Posture Rating Scale

Chart 1 Posture Evaluation

Figure 1 ▶ Comparison of bad and good posture.

Forward head

Kyphosis and sunken chest

Lordosis

Abdominal ptosis

Hyperextended knees

Bad Posture Good Posture

Flat arches

cor22568_ch11_225-264.indd 261 11/09/12 5:01 PM

F O S T E R , C E D R I C 1 6 9 2 T S

262

E va

lu a ti n g

P o

st u re

L a

b 1

1 B

Conclusions and Implications

Were you aware of the deviations that were found? Yes No

1. List the deviations that were moderate or severe (use several complete sentences).

2. In several sentences, describe your current posture status. Include in this discussion your overall assessment of your current posture, whether you think you will need special exercises in the future, and the reasons your posture rating is good or not so good.

cor22568_ch11_225-264.indd 262 17/08/12 9:31 PM

F O S T E R , C E D R I C 1 6 9 2 T S

263

P la

n n in

g a

n d

L o

g g

in g

E xe

rc ise

s: C a re

o f th

e B

a c k a

n d

N e c k

L a

b 1

1 C

Lab 11C Planning and Logging Exercises: Care of the Back and Neck

Name Section Date

Purpose: To select several exercises for the back and neck that meet your personal needs and to self-monitor prog- ress for one of these

Procedures

1. On Chart 1, check the tests from the Healthy Back Tests that you did not pass. Select at least one exercise from the group associated with those items. In addition, select several more exercises (a total of 8 to 10) that you think will best meet your personal needs. If you passed all of the items, select 8 to 10 exercises that you think will best prevent future back and neck problems. Check the exercises you plan to perform in Chart 1.

2. Perform each of the exercises you select 3 days in 1 week. 3. Keep a 1-week log of your actual participation using the last three columns in Chart 1. If possible, keep the log

with you during the day. Place a check by each of the exercises you perform for each day, including ones that you didn’t originally plan. If you cannot keep the log with you, fill in the log at the end of the day. If you choose to keep a log for more than 1 week, make extra copies of the log before you begin.

4. Answer the question in the Results section.

Check the tests you failed. ✓ Write in a selected exercise for each test that you can plan to perform this week.

[The core tests (5–10) may be used as

strengthening exercises]. Check the dates

you performed the exercises.

Day 1

Date:

Day 2

Date:

Day 3

Date:

1. Straight-leg lift

2. Thomas test

3. Ober test

4. Leg drop test

5. Isometric abdominal test

6. Isometric extensor test

7. Prone bridge

8. Quadruped stabilization

9. Right lateral bridge

10. Left lateral bridge

Chart 1 Back and Neck Exercise Plan

cor22568_ch11_225-264.indd 263 11/09/12 5:01 PM

F O S T E R , C E D R I C 1 6 9 2 T S

264

P la

n n in

g a

n d

L o

g g

in g

E xe

rc is

e s:

C a re

o f

th e B

a c k

a n d

N e c k

L a

b 1

1 C

Results

Did you do 8 to 10 exercises at least 3 days in the week? Yes No

Conclusions and Interpretations

1. Do you feel that you will use back and neck exercises as part of your regular lifetime physical activity plan, either now or in the future? Use several sentences to explain your answer.

2. Discuss the exercises you did. What exercises would you continue to do, and which ones would you change? Use several sentences to explain your answer.

cor22568_ch11_225-264.indd 264 17/08/12 9:31 PM

F O S T E R , C E D R I C 1 6 9 2 T S

289

Body Composition

LEARNING OBJECTIVES

After completing the study of this concept, you will be able to:

▶ Understand and interpret body composition measures. ▶ Describe common methods of assessing body composition. ▶ List health risks associated with overfatness. ▶ List health risks associated with excessively low body fatness. ▶ Identify and describe the origins of body fatness. ▶ Explain the relationship between physical activity and body composition and apply the FIT formula for achieving and maintaining a healthy body composition.

▶ Evaluate your body composition using several self-assessments and identify personal needs, set goals, and create a plan for achieving and maintaining a healthy body composition.

▶ Self-assess your daily energy expenditure.

C o

n c

e p

t 1 3

Nutrition and Body Composition ▶ Section V

Possessing an optimal amount

of body fat contributes to health

and wellness.

289

cor22568_ch13_289-322.indd 289 24/08/12 8:08 PM

F O S T E R , C E D R I C 1 6 9 2 T S

290 Section 5 ▶ Nutrition and Body Composition

Understanding and Interpreting Body Composition Measures Body composition is considered a component of

health-related fitness but can also be considered

a component of metabolic fitness. Body composi- tion is generally considered to be a health-related com- ponent of physical fitness. However, body composition is unlike the other parts of health-related physical fitness in that it is not a performance measure. Cardiovascular fitness, strength, muscular endurance, and flexibility can be assessed using movement or performance, such as run- ning, lifting, or stretching. Body composition requires no movement or performance. This is one reason some experts prefer to consider body composition as a com- ponent of metabolic fitness. Whether you consider body composition to be a part of health- related or metabolic fitness, it is an important health-related factor.

Standards have been established for healthy

levels of body fatness. Fat has important functions in the body, and it is distributed naturally into different tis- sues and storage depots. The indicator of percent body fat is typically used to reflect the overall fat content of the body. This indicator takes into account differences in body size and allows recommendations to be made for healthy levels of body fatness.

A certain minimal amount of fat is needed to allow the body to function. This level of essential fat is nec- essary for temperature regulation, shock absorption, and the regulation of essential body nutrients, including vita- mins A, D, E, and K. The exact amount of fat considered essential to normal body functioning has been debated, but most experts agree that males should possess no less than 5 percent and females no less than 10 percent. For females, an exceptionally low body fat percentage ( underfat ) is of special concern, particularly when asso- ciated with overtraining, low calorie intake, competitive

VIDEO 1

T he topic of overweight and obesity is in the news almost on a daily basis. Reports describe the health

effects of obesity, the social and environmental factors that contribute to obesity, and the overall impact that it has on society. Ironically, in a society in which being thin or lean is almost obsessively valued, the incidence of overweight and obesity continues to increase. The most recent statistics indicate that approximately 17 per- cent of youth and 66 percent of adults are overweight or obese in the United States. Surveys indicate that only 52 percent believe they are overweight. About one- third of American adults are classified as obese, but only 12 percent classify themselves in this category. A decade ago, no state had an obesity rate higher than 25 percent. Recent statistics indicate that no state has a rate lower than 20 percent, and 36 have obesity rates higher than 25 percent, with Mississippi having the highest rate (34 percent) and Colorado the lowest (21 percent).

The health implications of this obesity epidemic are hard to quantify and predict, but it is clear that obesity has become one of our greatest public health challenges. Health-care dollars spent annually on medi- cal conditions associated with obesity have been esti- mated at over $147 billion. It is estimated that by the year 2018 the cost will be $334 billion, accounting for 21 percent of health-care spending. Currently the yearly cost of medical care for the obese exceeds the cost for a normal-weight person by $2,460. When absenteeism from work is considered, the differences in health-care costs are even greater. Collectively, the obesity epidemic has placed a tremendous burden on our economy as well as on our health-care system. The problem is not unique to the United States, since similar trends are evident in almost all developed countries.

This concept describes issues associated with over- weight and obesity as well as the health risks associated with being too lean. Developing a healthy body image and avoiding disordered patterns of eating are critical for optimal health and wellness.

A CLOSER LOOK

ACTIVITY

Let’s Move! The childhood obesity epidemic is one of the biggest public health challenges facing our country. A number of national campaigns have been created to mobilize action and cre- ate change. These initiatives use a variety of social media to generate interest and momentum. The Let’s Move! campaign addresses childhood obesity by adopting a broad community

approach that enlists a variety of partners (community lead- ers, physicians, teachers, and parents) to help create healthier environments. The goal is to solve the epidemic of childhood obesity within a generation.

What changes in society would be needed to reach this goal?

cor22568_ch13_289-322.indd 290 24/08/12 8:09 PM

F O S T E R , C E D R I C 1 6 9 2 T S

Concept 13 ▶ Body Composition 291

stress, and poor diet. Amenorrhea may occur, placing the woman at risk for bone loss (osteoporosis) and other health problems. A body fat level below 10 percent is one of the criteria often used by clinicians for diagnosing eat- ing disorders, such as anorexia nervosa.

Figure 1 shows the health-related standards for body composition (percent body fat) for both males and females. Because individuals differ in their response to low fatness, a borderline range is provided above the essential fat (too low) zone. Values in this zone are not necessarily consid- ered to be healthy, but some individuals may seek to have lower body fat levels to enhance performance in certain sports. These levels can be acceptable for nonperform- ers if they can be maintained on a healthy diet and with- out overtraining. If symptoms such as amenorrhea, bone loss, and frequent injury occur, then levels of body fatness should be reconsidered, as should training techniques and eating patterns. For many people in training, maintaining performance levels of body fatness is temporary; thus, the risk for long-term health problems is diminished.

Fat that is stored above essential fat levels is classi- fied as nonessential fat . Just as percent body fat should not drop too low, it should not get too high. The healthy range for body fatness in males is between 10 and 20 per- cent, while the healthy range for women is between 17 and 28 percent. These levels are associated with good metabolic fitness, good health, and wellness. The mar- ginal zone includes levels that are above the healthy fit- ness zone but not quite into the range used to reflect obesity . The term obesity often carries negative connota- tions and stereotypes, but it is important to understand that it is a clinical term that simply means excessively high body fat. Lab 13A provides opportunities for you to assess your level of body fatness.

Health standards have been established for the

Body Mass Index. The Body Mass Index (BMI) is a commonly used indicator of overweight and obesity in our

society but is often misunderstood. The measure of BMI is basically an indicator of your weight relative to your height. It does not provide an indicator of body fatness, although BMI values tend to correlate with body fatness in most people. Because of this association, it is widely used in clini- cal settings and as a general indicator of body composition.

Because BMI is a frequently used measure, you should know how to calculate and interpret your BMI and your “healthy weight range.” Mathematically, BMI is calcu- lated with the following formula: BMI 5 weight (kg)/ (height [m] 3 height [m]). Instructions for calculating BMI, including the nonmetric formula and rating charts, are provided in the Lab Resource Materials (page 311). There are also many BMI calculators on the Internet that make it easy to calculate.

Too low Borderline Good fitness Marginal At risk

Too low Borderline Good fitness Overweight* Obesity*

Male 5 or less Body fatness (percent body fat) Female 10 or less

6–9

11–16

10–20

17–28

21–25

29–35

26+

36+

12 or less

13–16

17–25

26–30

30+

Male Body mass Index (kg/m2)Female

Figure 1 ▶ Health-related standards for body fatness (percent body fat) and body mass index. *Note: Based on international standards used for BMI classification.

Percent Body Fat The percentage of total body weight that is composed of fat. Essential Fat The minimum amount of fat in the body necessary to maintain healthful living. Underfat Too little of the body weight composed of fat. Amenorrhea Absent or infrequent menstruation. Nonessential Fat Extra fat or fat reserves stored in the body. Obesity A clinical term for a condition character- ized by an excessive amount of body fat (or extremely high BMI). Body Mass Index (BMI) A measure of body com- position using a height-weight formula. High BMI values have been related to increased disease risk. Overweight A clinical term that implies higher than normal levels of body fat and potential risk for development of obesity.

cor22568_ch13_289-322.indd 291 24/08/12 8:09 PM

F O S T E R , C E D R I C 1 6 9 2 T S

292 Section 5 ▶ Nutrition and Body Composition

The accepted international standards for defining overweight and obesity are the same for both men and women. BMI values over 25 are used to define over- weight , and values over 30 are used to define obesity. Figure 1 provides additional information concerning BMI standards.

While the use of BMI is widely accepted, it does have limitations. Individuals who do regular physical activity and who possess considerable muscle mass may show up as overweight using the BMI. This is because muscle weighs more than fat, but height and weight measurements do not detect differences in muscle and fat in the body.

Assessing body weight too frequently can result in

making false assumptions about body composition

changes. People vary in body weight from day to day and even hour to hour, based solely on their level of hydration. Short-term changes in weight are often due to water loss or gain, yet many people erroneously attribute the weight changes to their diet, a pill they have taken, or the exercise they recently performed. There is some evidence that monitoring weight daily can help normal- weight people from gaining weight. For people trying to lose weight, monitoring weight less frequently—once a week, for example—is more useful than taking daily or multiple daily measures. When you do weigh yourself, weigh at the same time of day, preferably early in the morning, because it reduces the chances that your weight variation will be a result of body water changes. Of course, it is best to use body composition assessments in addition to those based on body weight. These are described in the next section.

Methods Used to Assess Body Composition Methods of body composition vary in accuracy and

practicality. A number of techniques have been devel- oped to assess body composition. They vary in terms of practicality and accuracy, so it is important to understand the limitations of each method. Even established tech- niques have potential for error. The most common methods are summa- rized below.

Dual-energy absorptiometry (DXA) has emerged

as the accepted “gold standard” measure of body

composition. The DXA technique uses the attenuation of two energy sources to estimate the density of the body. A specific advantage of DXA is that it can provide whole-body measurements of body fatness as well as amounts stored in different parts of the body. An additional advantage is that it provides estimates of bone density. For the procedure, the person lies on a table and the machine scans up along

VIDEO 2

T E C H N O L O G Y U P D A T E

Counting Bites Pedometers are popular self-monitoring devices for tracking physical activity, but people also need ways to monitor how much they are eating. A new device called the Bite Counter tracks the number of bites a person takes. The device is worn on the wrist like a watch and it is able to detect the movement patterns associated with moving a fork or spoon from your plate to your mouth. Movements are apparently similar for foods eaten with your hands, such as an apple. According to the developer, it counts bites with 90 percent accuracy. The research group has determined that, on average, a bite typically contributes about 25 calories but this is obvi- ously highly variable.

Pedometers have proven valuable in helping people monitor

their steps in a day. Do you think this would help some people

monitor their calorie consumption?

ACTIVITY

Monitoring weight can be helpful, but measures of body fatness provide a better indication of body composition.

cor22568_ch13_289-322.indd 292 24/08/12 8:09 PM

F O S T E R , C E D R I C 1 6 9 2 T S

Concept 13 ▶ Body Composition 293

the body. While some radiation exposure is necessary with the procedure, it is quite minimal compared with X-ray and other diagnostic scans. Because the machine is quite expensive, this procedure is found only in medical centers and well-equipped research laboratories. The DXA (also called DEXA) procedure provides scientists with a highly accurate measure of body composition for research and a criterion measure that has been used to validate other, more practical measures of body composition.

Underwater weighing and Bod Pod are two highly

accurate methods. Underwater weighing is another excellent method of assessing body fatness. Before the development of DXA it was considered to be the “gold standard” method of assessment. In this technique, a person is weighed in air and underwater, and the differ- ence in weight is used to assess the levels of body fatness. People with a lot of muscle, bone, and other lean tissue sink like a rock in water because muscle and other lean tissue are dense. Fat is less dense, so people with more fat tend to float in a water environment. A limitation of this method is that participants must exhale all their air while submerged in order to obtain an accurate reading. Addi- tional error from the estimations of residual lung vol- umes also tends to reduce the accuracy of this approach.

A device called the Bod Pod uses the same principles as underwater weighing, but relies on air displacement to assess body composition. Evidence suggests that it pro- vides an acceptable alternative to underwater weighing and is particularly useful for special populations (obese older people and the physically challenged).

Skinfold measurements are a practical method

of assessing body fatness. About one-half of the body’s fat is located around the various body organs

and in the muscles. The other half of the body’s fat is located just under the skin, or in skinfolds. A skinfold ( Figure 2 ) is two thicknesses of skin and the amount of fat that lies just under the skin. By measuring skin- fold thicknesses of various sites around the body, it is possible to estimate total body fatness ( Figure 3 ). Skin- fold measurements are often used because they are relatively easy to do. They are not nearly as costly as underwater weighing and other methods that require expensive equipment. Research-quality skinfold cali- pers cost more than $100, but consumer models are available for $10 to $20.

In general, the more skinfolds measured, the more accurate the fatness estimate. However, measurements with two or three skinfolds have been shown to be rea- sonably accurate and can be done in a relatively short period. Two skinfold techniques are used in Lab 13A. You are encouraged to try both. With adequate training, most people can learn to use calipers to get a good esti- mate of fatness.

Bioelectric impedance analysis has become a

practical alternative for body fatness assessment. Bioelectric impedance analysis (BIA) ranks quite favor- ably for accuracy and has overall rankings similar to those of skinfold measurement techniques. The test can be per- formed quickly and is more effective for people high in body fatness (a limitation of skinfolds). The technique is based on measuring resistance to current flow. Elec- trodes are placed on the body and low doses of current are passed through the skin. Because muscle has greater water content than fat, it is a better conductor and has less resistance to current. The overall amount of resis- tance and body size are used to predict body fatness. The results depend heavily on hydration status, so do not test

Figure 2 ▶ Location of body fat.

Skin

Fat

Muscle

Bone

Figure 3 ▶ Measuring skinfold thickness with calipers.

Muscle

Skin

Skinfold

Caliper

Fat

cor22568_ch13_289-322.indd 293 24/08/12 8:09 PM

F O S T E R , C E D R I C 1 6 9 2 T S

294 Section 5 ▶ Nutrition and Body Composition

Health Risks Associated with Overfatness Obesity contributes directly and indirectly to a

number of major health problems. The presence of excess body fat impairs the function of most systems of the body (e.g., the cardiovascular system, the pulmonary system, the skeletal system, the reproductive system, and the metabolic system). It also increases risks for a variety of diseases, including a variety of cancers. The American Heart Association classifies obesity as a primary risk fac- tor, along with high blood pressure and high blood lipids (both associated with overweight and obesity). When all the evidence is considered, it is clear that overweight is associated with many health problems and obesity places a person at special risk (see Figure 4 ).

after exercising or immediately after eating or drinking. Accuracy is also affected by the quality of the equipment. Portable BIA scales are available that allow you to simply stand on metal plates to get an estimate of body fatness. These devices are easier to use but are less accurate than those that use electrodes for both upper and lower body.

Infrared sensors are sometimes used to assess

body fatness. Near-infrared interactance machines use the absorption of light to estimate body fatness. The tech- nique was originally developed to measure the fat con- tent of meats. Commercially available units for humans have not been shown to be effective for estimating body fat, and at least one company has faced sanctions from the government for selling an unapproved product. For this reason, this type of device is not recommended.

Pulmonary disease: • Abnormal function • Obstructive sleep apnea • Hypoventilation

Liver: • Liver disease • Cirrhosis

Gallbladder disease

Back pain

Pancreas: • Severe pancreatitis

Metabolism (Metabolic Syndrome) • High LDL cholesterol • Diabetes • Low insulin sensitivity • Increased apolipoprotein B • Increased C-reactive protein

Gynecological problems: • Abnormal menses • Infertility • Polycystic ovarian syndrome

Brain/Head: • Intracranial hypertension • Increased risk of stroke

Eyes: • Risk of cataracts

Heart: Coronary heart disease • Increased stress on heart • Hypertension

Cancer risk • Breast cancer • Uterine cancer • Cervical cancer • Colon cancer • Esophageal cancer • Pancreatic cancer • Kidney cancer • Prostate cancer

Osteoarthritis

Skin problems

Phlebitis • Venous stasis • Impaired circulation

Gout

Figure 4 ▶ Diseases and medical complications associated with obesity.

cor22568_ch13_289-322.indd 294 24/08/12 8:09 PM

F O S T E R , C E D R I C 1 6 9 2 T S

Concept 13 ▶ Body Composition 295

Studies indicate that overweight and obesity and associated unhealthy lifestyles (e.g., sedentary living and unhealthy eating) are the second leading actual cause of death. One study indicates that obesity and smoking are equal in their overall burden on the health-care system. Smoking has decreased 18.5 percent in the past two decades, while obesity rates increased by 85 percent. If current trends continue, obesity and overweight will soon surpass smoking as the number one cause of early death.

Obesity contributes to early death. In addition to the higher incidence of certain diseases and health problems, people who are moderately overfat have a 40 percent higher than normal risk of shortening their lifespan. More severe obesity results in a 70 percent higher than normal death rate. A study of nearly one million adults suggests that obesity can cut 8 to 10 years from life expectancy. Another recent study indicates that extreme obesity shortens life by 12 years.

Statistics indicate that underweight people also have a higher than normal risk for premature death. Though adequate evidence shows extreme leanness (e.g., anorexia nervosa) can be life threatening, underweight people may have lost weight because of a medical condition such as cancer. It appears that the medical problems are often the reason for low body weight rather than low body weight being the source of the medical problem. Most experts agree that people who are free from disease and who have lower than average amounts of body fat have a lower than average risk for premature death.

Physical fitness provides protection from the health

risks of obesity. A general assumption in our society is that if you are thin, you are probably fit and healthy and if you are overweight, you are unfit and unhealthy. A series of studies from the Aerobic Center Longitudinal Study (a large cohort study of patients from the Cooper Clinic in Dallas, Texas) has demonstrated that the health risks associated with overweight are greatly reduced by regu- lar physical activity and reasonable levels of cardiovascular

fitness (see Figure 5 ). In fact, the findings consistently show that active people who have a high BMI are at less risk than inactive people with normal BMI levels. Even high levels of body fatness may not be especially likely to increase disease risk if a person has good metabolic fit- ness as indicated by healthy blood fat levels, normal blood pressure, and normal blood sugar levels. It is when several of these factors are present at the same time that risk lev- els increase dramatically. For this reason, it is important to consider your cardiovascular and metabolic fitness levels before drawing conclusions about the effects of high body weight or high body fat levels on health and wellness. This information also points out the importance of periodically assessing your cardiovascular and metabolic fitness levels.

Excessive abdominal fat and excessive fat of

the upper body can increase the risk for various

diseases. The location of body fat can influence the health risks associated with obesity. Fat in the upper part of the body is sometimes referred to as “Northern Hemisphere” fat, and a body type high in this type of fat is called the “apple” shape (see Figure 6 ). Upper-body fat is also referred to as android fat because it is more char- acteristic of men than women. Postmenopausal women typically have a higher amount of upper body fat than premenopausal women. Lower body fat, such as in the hips and upper legs, is sometimes referred to as “South- ern Hemisphere” fat. This body type is called the “pear”

0.0

0.5

1.0

1.5

2.0

2.5

R el

at iv

e ri

sk o

f al

l- ca

u se

m o rt

al it y

Normal

Fit Unfit

Overweight Obese

Figure 5 ▶ Risks of fatness vs. fitness. Source: Lee, C. D., et al.

Figure 6 ▶ Visceral, or abdominal, fat is associated with increased disease risk.

Visceral fat

Subcutaneous fat

Kidney

Liver Abdominal

muscle

Spine

Skin

cor22568_ch13_289-322.indd 295 24/08/12 8:09 PM

F O S T E R , C E D R I C 1 6 9 2 T S

296 Section 5 ▶ Nutrition and Body Composition

shape. Lower-body fat is also referred to as gynoid fat because it is more characteristic of women than men.

Body fat located in the core of the body is referred to as central fat or visceral fat. Visceral fat is located in the abdominal cavity (see Figure 6 ), as opposed to subcutane- ous fat, which is located just under the skin. Though sub- cutaneous fat (skinfold measures) can be used to estimate body fatness, it is not a good indicator of central fatness. Your waist size is a useful indicator of visceral fat distri- bution. It can be used alone, in combination with BMI, in combination with your gender and height, and/or in combination with hip size (waist-to-hip ratio) to deter- mine health risk (see Lab Resource Materials). Visceral fat is considered more harmful than other forms and is associ- ated with high blood fat levels as well as other metabolic problems. It is also associated with high incidence of heart attack, stroke, chest pain, breast cancer, and early death.

Part of the benefit of aerobic activity for health appears to be its ability to promote the preferential loss of abdom- inal body fat. Several recent studies have shown that higher levels of activity and/or higher cardiorespiratory fitness are associated with lower levels of abdominal body fatness independent of body mass index. In other words, if one person who is fit and active has the same height and weight as a less active person, he or she will likely have a lower amount of abdominal fat. These studies provide a clear understanding of how fitness may protect against the health risks of obesity and improve overall health.

Health effects of obesity may be mediated by

circulating “adipokines.” Research has recently shown that the fat cell is not only a storage depot, but also an active protein-secreting organ. The biomolecules secreted by adipose tissue are known as adipokines or adipocyto- kines. A number of adipokines have been identified, includ- ing adiponectin, visfatin, resistin, and leptin. Each has an important role, but adiponectin appears to play a particu- larly important role in energy balance, insulin resistance, and atherosclerosis. Studies show that adiponectin has an anti-atherosclerotic effect while also reducing platelet aggregation, which can contribute to formation of blood clots. In contrast, adiponectin deficiency appears to lead to metabolic dysfunction, insulin resistance, fatty liver dis- ease, and also to a wide array of cancers. Current evidence supports that aerobic exercise, alone or combined with hypocaloric diet, improves symptoms of the metabolic syndrome, possibly by altering levels of adipokines.

Health Risks Associated with Excessively Low Body Fatness Excessive desire to be thin or low in body weight

can result in health problems. In Western society, the near obsession with thinness has been, at least in part,

responsible for eating disorders. Eating disorders, or altered eating habits, involve extreme restriction of food intake and/or regurgitation of food to avoid digestion. The most common disorders are anorexia nervosa, binge-eat- ing, bulimia, and anorexia athletica. All of these disorders are most common among highly achievement-oriented girls and young women, although they affect virtually all segments of the population. Patterns of “disordered eat- ing” are not the same as clinically diagnosed eating disor- ders. People who adopt disordered eating, however, tend to have a greater chance of developing an eating disor- der. It is interesting to note that in 1974 the percentage of underweight Americans was 3.6. Today half that percent- age (1.8) of Americans is classified as underweight.

Anorexia nervosa is the most severe eating

disorder. If untreated, it is life threatening. Anorexics restrict food intake so severely that their bodies become emaciated. Among the many characteristics of anorexia nervosa are fear of maturity and inaccurate body image. The anorexic starves himself or herself and may exercise compulsively or use laxatives to prevent the digestion of food in an attempt to attain excessive leanness. The anorexic’s self-image is one of being too fat, even when the person is too lean for good health. Assessing body fatness using procedures such as skinfolds and observa- tion of the eating habits may help identify people with anorexia. Among anorexic girls and women, development of an adult figure is often feared. People with this disorder must obtain medical and psychological help immediately, as the consequences are severe. About 25 percent of those with anorexia do compulsive exercise in an attempt to stay lean. Anorexia is a very serious medical condition that deserves more discussion than can be provided in this book.

Binge-eating is the most common eating

disorder in the United States. According to the American Psychiatric Association, you are a binge-eater if you meet these three criteria: (1) eat larger amounts of food than most people eat in a short time; (2) feel out of control while bingeing at least once a week for three months; and (3) do three or more behaviors, such as feeling depressed about your binges, eating alone to avoid embarrassment about amounts eaten, eating large amounts when not hungry, eating more rapidly than normal, or continuing to eat when you feel full. While binge-eating can be a serious disorder, it can be treated effectively. One study showed that 64 percent of binge- eaters who received therapy and reading material were binge free after only one year.

Bulimia is a common eating disorder characterized

by bingeing and purging. Disordered eating pat- terns become habitual for many people with bulimia.

cor22568_ch13_289-322.indd 296 24/08/12 8:09 PM

F O S T E R , C E D R I C 1 6 9 2 T S

Concept 13 ▶ Body Composition 297

A bulimic might binge after a relatively long period of dieting and consume excessive amounts of junk foods containing empty calories. After a binge, the bulimic purges the food by forced regurgitation or the use of laxatives. Another form of bulimia is bingeing on one day and starving on the next. The consequences of buli- mia include serious mental, gastrointestinal, and den- tal problems. Bulimics may or may not be anorexic. It may not be possible to use measures of body fatness to identify bulimia, as the bulimic may be lean, normal, or excessively fat.

Anorexia athletica is a more recently identified

eating disorder that appears to be related to

participation in sports and activities emphasizing

body leanness. Studies show that participants in sports such as gymnastics, wrestling, and bodybuilding and activities such as ballet and cheerleading are most likely to develop anorexia athletica. This disorder has many of the symptoms of anorexia nervosa, but not of the same severity. In some cases, anorexia athletica leads to anorexia nervosa.

Female athlete triad is an increasingly common

condition among female athletes. The triad refers to the presence of three related and linked symptoms that affect some women athletes (eating disorders/low energy availability, amenorrhea, and decreased bone mineral density). The conditions are linked because low body fat levels lead to the amenorrhea. The alterations in men- strual cycles lead to low levels of estrogen which sub- sequently lead to the reduced bone density and risk for osteoporosis.

The female athlete triad is one of the more challeng- ing conditions to treat because it often goes undetected. Once identified or diagnosed, it is hard to change because the three components of the triad are thought to be linked pathophysiologically. The athlete is very serious about performance and has likely developed altered eating patterns to control body weight. Efforts to bring about change often result in resistance, since the compulsion to be thin and perform well overrides other concerns, such as eating well, moderating exer- cise, and having a normal menstrual cycle. The ACSM recommends regular screening exams to identify those with the triad and rule changes in women’s sports to “discourage unhealthy weight loss practices.” Nutrition counseling is recommended for those with the triad, and psychotherapy is recommended for athletes with eating disorders.

Many female athletes train extensively and have rel- atively low body fat levels but experience none of the symptoms of the triad. Eating well, training properly, using stress-management techniques, and monitoring health symptoms are the keys to their success.

Muscle dysmorphia is an emerging problem among

male athletes. Muscle dysmorphia is a body dysmor- phic disorder in which a male becomes preoccupied with the idea that his body is not sufficiently lean and/ or muscular. Athletes with this condition may be more inclined to use performance-enhancing drugs, to exercise while sick, or to have an eating disorder. Additional risks include depression and social isolation.

Fear of obesity and purging disorder are other

identified conditions. Fear of obesity is most common among achievement-oriented teenagers who impose a self-restriction on caloric intake because they fear obe- sity. Consequences include stunting of growth, delayed puberty, delayed sexual development, and decreased physical attractiveness. Purging disorder, a condition that results in purging similar to bulimia, but without the bingeing, has recently been identified. People with these conditions should seek assistance.

The Origin of Fatness Obesity is a multifactorial disease that is

influenced by both genetics and the environment.

The evidence documenting a genetic component to human obesity is quite compelling. There is clear cluster- ing of obesity within families, and studies have docu- mented high concordance of body composition in identical twins. Studies of adopted children have also demonstrated that there is an association between the BMI of adoptees and the biologic parents, but not with the adoptee parents. Despite the clear evidence, the role of genetic factors is still not well understood. Genetic mapping studies suggest that a number of genes may work in combination to influence susceptibility to obe- sity. These susceptibility genes may not lead directly to obe- sity but may predispose a person to overweight or obesity if exposed to certain environmental conditions.

Thus, the prevailing model guiding obesity research is that complex genetic and environmental variables inter- act to increase potential risks for obesity. Genetic factors, by themselves, cannot account for the increases in obesity because the gene pool does not change that rapidly. Recent research has shown that lack of sleep can increase risk for overweight (particularly in youth). Excessive screen time (TV and computer use) and sitting time increase risk of obesity. Future research will allow genetic factors to be integrated with behavioral and envi- ronmental data so that the combined effects can be better understood.

Body weight is regulated and maintained through

complex regulatory processes. Some scholars have suggested that the human body type, or somatotype ,

VIDEO 3

cor22568_ch13_289-322.indd 297 24/08/12 8:09 PM

F O S T E R , C E D R I C 1 6 9 2 T S

298 Section 5 ▶ Nutrition and Body Composition

is inherited. Clearly, some people have more diffi- culty than others controlling fatness, and this may be because of their somatotype and genetic predisposition. Regulatory processes appear to balance energy intake and energy expenditure so that body weight stays near a biologically determined set-point . The regulation is helpful for maintaining body weight but can be frustrat- ing for people trying to lose weight. If a person slowly tries to cut calories, the body perceives an energy imbal- ance and initiates processes to protect the current body weight. The body can accommodate to a new, higher set-point if weight gain takes place over time, but there is greater resistance to adopting a lower set-point. Many people lose weight, only to see the weight come back months later. One of the reasons exercise is so critical for weight maintenance is that it may help in resetting this set-point.

In recent years, the mechanisms involved in the reg- ulation of the biological set-point have become better understood. The current view is that there are complex feedback loops among fatty tissues, the brain, and endo- crine glands, such as the pancreas and the thyroid. The compound leptin plays a crucial role in altering appetite and in speeding up or slowing down the metabolism. Leptin levels rise during times of energy excess in order to suppress appetite and fall when energy levels are low to stimulate appetite. Resistance to leptin has been hypoth- esized as a possible contributor to obesity. A number of other compounds also appear to be involved in the com- plex processes regulating energy balance. Problems with the thyroid gland can lead to impairments in metabolic regulation, but these do not contribute to overfatness in most people.

Fatness early in life leads to adult fatness.

Although there are exceptions, individuals who are overweight or obese as children are more likely to be overweight or obese as adults. One explanation for this

is that overfatness in children causes the body to pro- duce more fat cells. Research has even suggested that the neonatal environment that the child is exposed to during development may also influence future risks for obesity. It appears that hormones and lipids circulating in the maternal blood can interact with genetic factors to establish metabolic conditions that contribute to over- fatness. While these factors influence body composition, it is still possible to improve body composition by adopt- ing healthy lifestyles.

Maintaining healthy levels of body fat is an impor- tant objective for children and adults. It was previously thought that only adult obesity was related to health problems, but it is now apparent that teens who are over- fat are at a greater risk for heart problems and cancer than leaner peers. Obese children have been found to have symptoms of “adult-onset diabetes,” and obese chil- dren have a higher than normal risk of premature death, indicating that the effects of obesity can impair health, even for young people. Concerns about the current and future implications of childhood obesity have made it one of the greatest public health concerns facing our country. A variety of national organizations have targeted obesity prevention as a top priority. (See information on the Let’s Move! campaign on page 290.) The momentum gener- ated from these campaigns is encouraging, but it must translate into progressive policies and programming to create such a change.

Changes in basal metabolic rate can be the cause

of obesity. Your basal metabolic rate (BMR) is the largest component of total daily energy expenditure. BMR is typically expressed in the number of calories needed to maintain your body functions under resting conditions. When resting, your body expends calories because your heart is pumping and other body organs are working. Processing the food you eat also expends calories. People with more lean tissue have a higher BMR

Lack of Sleep Is Associated with Overweight Most people know that sleep is important for good health, but it also may contribute to

maintaining a healthy weight. A number of studies have demon- strated inverse associations between sleep and overweight but it has proven difficult to understand the biological mechanisms. Recent studies suggest that sleep loss may impose demands on the metabolism that trigger hormonal and behavior adap- tations that increase food intake and conservation of energy.

Scientists speculate that this response may have evolved as a way for primitive man to conserve energy during periods with limited food availability but it is problematic in modern soci- ety with food abundance. The findings point out how different lifestyles can interact to influence weight status and wellness .

How do these findings about sleep influence your views about health

and wellness?

L M f

ACTIVITY

In the News

cor22568_ch13_289-322.indd 298 24/08/12 8:09 PM

F O S T E R , C E D R I C 1 6 9 2 T S

Concept 13 ▶ Body Composition 299

than those with less lean tissue and greater amounts of body fat. People that are physically active will also have a higher BMR on days they exercise, contributing to long- term weight control.

BMR is highest during the growing years. The amount of food eaten increases to support this increased energy expenditure. When a person reaches full growth, the BMR is determined primarily by the amount of muscle mass a person has. Regular physical activity throughout life helps keep the muscle mass higher, resulting in a higher BMR. Evidence suggests that regular exercise can contribute in other ways to increased BMR. For example, BMR can stay elevated for up to 10 hours following a bout of vigorous physical activity. The higher BMR helps burn extra calories during the day.

“Creeping obesity” is a problem as you grow

older. With age, people tend to become less active, causing declines in BMR. Caloric intake does seem to decrease somewhat with age, but the decrease does not adequately compensate for the decreases in BMR and activity levels. For this reason, body fat increases gradu- ally with age for the typical person (see Figure 7 ). This increase in fatness over time is commonly referred to as “creeping obesity” because the increase in fatness is gradual. For a typical person, creeping obesity can result in a gain of 1/2 to 1 pound per year. People who stay active can keep muscle mass high and delay changes in BMR. For those who are not active, it is suggested that caloric intake decrease by 3 percent each decade after 25 so that by age 65 caloric intake is at least 10 percent less than it was at age 25. The decrease in caloric intake for active people need not be as great.

The Relationship between Physical Activity and Body Composition A combination of regular physical activity and

dietary restriction is the most effective means of

losing body fat. Studies indicate that regular physical activity combined with dietary restriction is the most effective method of losing fat. Diet alone can contribute to weight loss, but much of this loss is actually lean tis- sue. When physical activity and diet are both used in a

Somatotype A term that refers to a person’s body type. One researcher (Sheldon) suggested that there are three basic body types: ectomorph (linear), meso- morph (muscular), and endomorph (round). Set-point A theoretical concept that describes the way the body protects current weight and resists change. Basal Metabolic Rate (BMR) Energy expenditure in a basic, or rested, state. Calories Units of energy supplied by food; the quantity of heat necessary to raise the temperature of a kilogram of water 18C (actually, a kilocalorie, but usually called a calorie for weight control purposes). Diet The usual food and drink for a person or an animal.

500

1000

1500

2000

2500

3000

0 35 45 55 65

Calorie Intake Calorie Expenditure Basal Metabolic Rate Physical Activity

Bo dy

Fa tne

Figure 7 ▶ Creeping obesity.

Health is available to Everyone for a

Lifetime, and it’s Personal

The “freshman 15” is a term used for the weight gain that often happens to college students during their first year in college. Research verifies that first year col- lege students do gain weight though the average gain is closer to 6–9 pounds. Over four years of college the average student gains 10 pounds. Students attribute the gain to factors such as being less active, eating when stressed, and drinking more. While this is common among college students, the weight proves difficult for many students to lose after college.

What steps can you take to maintain a healthy weight during

the college years?

ACTIVITY

cor22568_ch13_289-322.indd 299 24/08/12 8:09 PM

F O S T E R , C E D R I C 1 6 9 2 T S

300 Section 5 ▶ Nutrition and Body Composition

weight loss program, the same amount of weight may be lost but more of it is from fat. This is obviously beneficial for appearance and for participation in physical activity, but it can also help maintain resting metabolic rate at a higher level. This can contribute to further weight loss or facilitate weight maintenance. For optimal results, all weight loss programs should combine a lower caloric intake with a good physical exercise program. Table 1 presents thresholds of training and target zones for body fat reduction, including information for both physical activity and diet. A general guideline is to try to lose no more than 1 to 2 pounds a week. Because a pound of fat contains 3,500 calories (see note in Table 1 ), this requires a caloric deficit of approximately 500 calories per day. Individuals interested in maintaining body composition should aim for caloric balance . Individuals who want to increase lean body mass need to increase caloric intake while carefully increasing the inten- sity and duration of their physical activity (mainly muscular activity).

Physical activity can help expend extra energy

needed to promote weight loss. The ACSM and national activity guidelines recommend a minimum of 30 minutes of moderate to vigorous activity a day or 150 minutes per week (see Table 1 ) but acknowledge that this may not be enough for some people. More time is often needed either to maintain weight over time or to

lose weight. The ACSM guidelines suggest that it may be necessary to work progressively up to 200 to 300 minutes a week to expend enough calories to lose weight. One study found that women who maintained weight across the lifespan average approximately 60 minutes of activity per day. Calories expended in various activities are pre- sented in Table 2.

Energy balance principles apply for both weight

maintenance and weight gain. Table 1 focuses on weight loss because overweight and obesity are preva- lent in our society and many adults are currently diet- ing (approximately 33 percent), while another one-third are taking other steps to lose weight. For normal-weight people, maintenance is important, and balancing energy intake with energy expenditure is the key. There is little doubt that preventing overweight in the first place will help people avoid the more difficult task of losing weight. For those interested in weight gain, extra calorie intake is required, following the sound eating practices described in Concepts 14 and 15. Resistance training is also recom- mended because it builds muscle mass.

Table 1 ▶ Threshold of Training and Target Zones for Body Fat Reduction

Threshold of Training* Target Zones*

Physical Activity Diet Physical Activity Diet

Frequency • To be effective, activity must be regular, preferably daily, though fat can be lost over the long term with almost any frequency that results in increased caloric expenditure.

• Reduce caloric intake consistently and daily. To restrict calories only on certain days is not best, though fat can be lost over a period of time by reduc- ing caloric intake at any time.

• Daily moderate activity is recommended. For people who do regular vigorous activity, 3 to 6 days per week may be best.

• It is best to diet consis- tently and daily.

Intensity • To lose 1 pound of fat, you must expend 3,500 calories more than you normally expend.

• To lose 1 pound of fat, you must eat 3,500 calories fewer than you normally eat.

• Slow, low-intensity aerobic exercise that results in no more than 1 to 2 pounds of fat loss per week is best.

• Modest caloric restriction resulting in no more than 1 to 2 pounds of fat loss per week is best.

Time • To be effective, exercise must be sustained long enough to expend a considerable number of calories. At least 15 minutes per exercise bout are necessary to result in consistent fat loss.

• Eating moderate meals is best. Do not skip meals.

• Exercise durations similar to those for achieving aer- obic cardiovascular fitness seem best. Exercise of 30 to 60 minutes in duration is recommended.

• Eating moderate meals is best. Skipping meals or fasting is not most effective.

Note: A gram of fat is 9 calories; thus, a pound is equal to 4,086 calories (9 cal/g 3 454 g/pound). However, fat in the body is 10 percent water and contains some protein and minerals that reduce the effective caloric equivalent to 3,500 calories (the accepted standard).

*It is best to combine exercise and diet to achieve the 3,500-calorie imbalance necessary to lose a pound of fat. Using both exercise and diet in the target zone is most

effective.

VIDEO 4

Caloric Balance Consuming calories in amounts equal to the number of calories expended.

cor22568_ch13_289-322.indd 300 24/08/12 8:09 PM

F O S T E R , C E D R I C 1 6 9 2 T S

Concept 13 ▶ Body Composition 301

Table 2 ▶ Calories Expended per Hour in Various Physical Activities (Performed at a Recreational Level)*

Calories Used per Hour

Activity 100 lb. (46 kg) 120 lb. (55 kg) 150 lb. (68 kg) 180 lb. (82 kg) 200 lb. (91 kg)

Archery 180 204 240 276 300 Backpacking (40-lb. pack) 307 348 410 472 513

Badminton 255 289 340 391 425 Baseball 210 238 280 322 350

Basketball (half-court) 225 255 300 345 375 Bicycling (< 10 mph) 182 218 273 327 364

Bowling 136 164 205 245 273 Canoeing 227 273 341 409 455

Circuit training 247 280 330 380 413 Dance, aerobics 315 357 420 483 525

Dance, ballet (choreographed) 240 300 360 432 480 Dance, modern (choreographed) 240 300 360 432 480

Dance, social 205 245 307 368 409 Fencing 225 255 300 345 375

Fitness calisthenics 232 263 310 357 388 Football 225 255 300 345 375

Golf (walking) 250 300 375 450 500 Gymnastics 232 263 310 357 388

Handball 450 510 600 690 750 Hiking 225 255 300 345 375

Horseback riding 182 218 273 327 364 Interval training 487 552 650 748 833

Jogging (5 1/2 mph) 487 552 650 748 833 Judo/karate 232 263 310 357 388

Mountain climbing 450 510 600 690 750 Pool/billiards 97 110 130 150 163

Racquetball/paddleball 450 510 600 690 750 Rope jumping (continuous) 525 595 700 805 875

Rowing, crew 615 697 820 943 1025 Running (10 mph) 625 765 900 1035 1125

Sailing (pleasure) 135 153 180 207 225 Skating, ice 262 297 350 403 438

Skating, roller/inline 262 297 350 403 438 Skiing, cross-country 318 382 477 573 636

Skiing, downhill 450 510 600 690 750 Soccer 405 459 540 621 775

Softball (fast-pitch) 210 238 280 322 350 Softball (slow-pitch) 217 246 290 334 363

Surfing 416 467 550 633 684 Swimming (fast laps) 420 530 630 768 846

Swimming (slow laps) 273 327 409 491 545 Table tennis 182 218 273 327 364

Tennis 315 357 420 483 525 Volleyball 262 297 350 403 483

Walking 173 207 259 311 346 Waterskiing 306 390 468 564 636

Weight training 352 399 470 541 558

*Locate your weight to determine the calories expended per hour in each of the activities shown in the table based on recreational involvement. More vigorous activity,

as occurs in competitive athletics, may result in greater caloric expenditures.

Source: Corbin and Lindsey.

cor22568_ch13_289-322.indd 301 24/08/12 8:09 PM

F O S T E R , C E D R I C 1 6 9 2 T S

302 Section 5 ▶ Nutrition and Body Composition

Whether you are trying to maintain, gain,

or lose weight, know how many calories you

consume in food and expend in the activities you

perform. Appendix C provides estimates of calories in some common foods. The MyPlate (Food-A-Pedia)

website included in the Web Resources for this con- cept provides a comprehensive list of calories in foods.

Strength training can be effective in maintaining

a desirable body composition. Performing exercises from the strength and muscular endurance level of the physical activity pyramid can be effective in maintaining desirable body fat levels. People who do strength training increase their muscle mass (lean body mass). This extra muscle mass expends extra calories at rest, resulting in a higher metabolic rate. Also, people with more muscle mass expend more calories when doing physical activity.

Water contains zero calories and is an excellent alternative to sugary drinks that are high in calorie content.

Strategies for Action

Doing several self-assessments can

help you make informed decisions

about body composition. In Labs 13A and 13B, you will take various body composition self-assessments. It is important that you take all of the measurements and con- sider all of the information before making final decisions about your body composition. Each self-assessment tech- nique has strengths and weaknesses to be aware of when you make personal decisions. The importance you place on

one particular measure may be different from the importance another person places on that measure; you are a unique individual and should use information that is more relevant for you personally.

Self-assessment results for body composition are personal

and confidential. There are steps that can be taken to assure confidentiality. When performing the self-assessments, be aware of the following:

Physical activity can help in regulating body fatness.

VIDEO 5

cor22568_ch13_289-322.indd 302 24/08/12 8:09 PM

F O S T E R , C E D R I C 1 6 9 2 T S

Concept 13 ▶ Body Composition 303

Web Resources Centers for Disease Control and Prevention BMI Information

www.cdc.gov/nccdphp/dnpa/bmi/adult_BMI/about_

adult_BMI.htm

Centers for Disease Control and Prevention Growth Chart Information www.cdc.gov/growthcharts

FDA Consumer www.fda.gov/fdac Let’s Move! Campaign www.letsmove.gov MyPlate www.choosemyplate.gov MyPlate Food-A-Pedia www.choosemyplate

.gov/SuperTracker/foodapedia.aspx

MyPlate Food Tracker www.choosemyplate .gov/SuperTracker/foodtracker.aspx

National Heart Lung and Blood Institute (BMI Calculator) www.nhlbisupport.com/bmi

Nutriwatch (nutrition facts and fallacies) www.nutriwatch.org Partnership for Healthy Weight Management www.ftc

.gov/bcp/edu/pubs/consumer/health/hea05.pdf

Shape Up America www.shapeup.org STOP Obesity Alliance www.stopobesityalliance.org Surgeon General’s Call to Reduce Overweight and Obesity

www.surgeongeneral.gov/library/calls/obesity/index

.html

“We Can” Program www.nhlbi.nih.gov/health/public/heart/ obesity/wecan/index.htm

Suggested Readings ACSM. 2010. ACSM’s Resource Manual for Guidelines for Exer-

cise Testing and Prescription. 6th ed. Philadelphia: Lippincott, Williams & Wilkins, Chapter 10.

Ball, S., P. Swan, and T. Altena. 2006. Skinfold assessment: Accuracy and application. Measurement in Physical Education and Exercise Science 10(4):255–264.

Chan, R. S., and J. Woo. 2010. Prevention of overweight and obesity: How effective is the current public health approach. International Journal of Environmental Research on Public Health 7(3):765–783.

Christakis, N. A., and J. H. Fowler. 2007. The spread of obesity in a large social network over 32 years. New England Journal of Medicine 375(4):370–379.

Cohen, D. A., et al. 2010. Not enough fruit and vegetables or too many cookies, candies, salty snacks, and soft drinks? Public Health Reports 125(1):88–95.

Eisenmann, et al. 2008. Combined influence of physical activity and television viewing on the risk of overweight in US youth. International Journal of Obesity 32(4):613–618.

Finkelstein, E. A. 2010. Individual and aggregate years of life lost associated with overweight and obesity. Obesity 18(2):333–339.

Flegal, K. M., and B. I. Graubard. 2009. Estimates of excess deaths associated with body mass index and other anthro- pometric variables. American Journal of Clinical Nutrition 89(4):1213–1219.

Flegal, K. M., et al. 2010. Prevalence and trends in obesity among U.S. adults, 1999–2008. Journal of the American Medical Association 303(3):235–241.

Hardy, L. L., et al. 2010. Screen time and metabolic risk factors among adolescents. Archives of Pediatric and Adolescent Medicine 164(7):643–649.

Herman, K. M., et al. 2009. Tracking of obesity and physical activity from childhood to adulthood: The Physical Activity

1. If doing a self-assessment around other people makes you self-conscious, do the measurement in private. If the measurement requires the assistance of another person, choose a person you trust and feel comfortable with.

2. Estimates of body composition from even the best tech- niques may be off by as much as 2 to 3 percent. The values should be interpreted only as estimates.

3. The formulas used to determine body fatness from skin- folds and other procedures are based on typical body types. Measurement will be larger for the very lean and for people with higher than normal levels of fat.

4. Some measurements, such as the thigh skinfold, are hard to take on some people. This is one reason two different skinfold procedures are presented.

5. Self-assessments require skill. With practice, you can become skillful in making measurements. Your first few attempts will, no doubt, lack accuracy.

6. Use the same measuring device each time you measure (scale, calipers, measuring tape, etc.). This assures that

any measurement error is constant and allows you to track your progress over time.

7. Once you have tried all of the self-assessments in Lab 13A, choose the ones you want to continue to do and use the same measurement techniques each time. Consider assessing your body composition with some of the other techniques described in the concept.

Estimate your BMR to determine the number of calories

you expend each day. In Lab 13C, you can estimate your BMR, giving you an idea of how much energy you expend when you are resting. Use this information together with the information about the energy you expend in activities to help you balance the calories you consume with the calories you expend each day.

Log your daily activities to determine the number of calories

you expend each day in these activities. In Lab 13C, you will also log the activities you perform in a day. Then deter- mine your energy expenditure in these activities. Combine this information with the information about your basal metabolism to determine your total daily energy expenditure.

ACTIVITY

cor22568_ch13_289-322.indd 303 10/09/12 7:34 PM

F O S T E R , C E D R I C 1 6 9 2 T S

304 Section 5 ▶ Nutrition and Body Composition

Penev, P. D. 2012. Update on energy homeostasis and insufficient sleep. Journal of Clinical Endocrinology and Metabolism. March.

Perusse, L., et al. 2005. The human obesity gene map: The 2004 update. Obesity Research 13(3):381–490.

Phillips, K. A., et al. 2010. Body dysmorphic disorder: Some key issues for DSM-V. Depression and Anxiety 27(6):573–591.

Prospective Studies Collaboration. 2009. Body-mass index and cause-specific mortality in 900,000 adults: Collaborative analyses of 57 prospective studies. Lancet 373(9669):1083–1096.

Ruiz, J. R., et al. 2010. Attenuation of the effect of the FTO rs9939609 polymorphism on total and central body fat by physical activity in adolescents: The HELENA Study. Archives of Pediatric and Adolescent Medicine 164(4):328–333.

Shehzad, A., et al. 2012. Adiponectin: Regulation of its produc- tion and its role in human diseases. Hormones 11(1):8–20.

Stewart, S. 2009. Forecasting the effects of obesity and smoking on U.S. life expectancy. New England Journal of Medicine 361(23):2252–2260.

Surgeon General’s Vision for a Healthy and Fit Nation. 2010 (fact sheet). Available at www.surgeongeneral.gov .

Vella-Zarb, R. A., and F. J. Elgar. 2009. The ‘freshman 5’: A meta-analysis of weight gain in the freshman year of college. Journal of American College Health 58(2):161–166.

Wang, Y., et al. 2008. Will all Americans become overweight or obese? Estimating the progression and cost of the U.S. obesity epidemic. Obesity 16(10):2323–2330.

Westcott, W. 2009. ACSM strength training guidelines: Role in body composition and health enhancement. ACSM’s Health and Fitness Journal 13(4):14–22.

Yates, T., et al. 2012. Self-reported sitting time and markers of inflammation, insulin resistance, and adiposity. American Journal of Preventive Medicine 42(1):1–7.

Longitudinal Study. International Journal of Pediatric Obesity 4(4):281–288.

Herman, K. M., et al. 2012. Physical activity, body mass index, and health-related quality of life in Canadian adults. Medicine and Science in Sports and Exercise 44(4):625–636.

John, J., et al. 2010. Recent economic findings on childhood obesity: Cost-of-illness and cost-effectiveness of interven- tions. Current Opinions in Clinical Nutrition and Metabolic Care 13(3):305–313.

Keel, P. K., et al., 2007. Clinical features and psychological response to a test meal in purging disorder and bulimia nervosa. Archives of General Psychiatry 64:1058–1066.

Kuk, J. L., et al. 2006. Visceral fat is an independent predictor of all-cause mortality in men. Obesity Research 14:336–341.

Kwon, S., et al. 2011. Effects of adiposity on physical activity in childhood: Iowa bone development study. Medicine & Science in Sports & Exercise 4(3):443–448.

Li, S., and R. J. Loos. 2008. Progress in the genetics of common obesity: Size matters. Current Opinions in Lipidology 19(2):113–121.

Liou, Y. M., et al. 2010. Obesity among adolescents: Seden- tary leisure time and sleeping as determinants. Journal of Advances in Nursing 66(6):1246–1256.

Lynch, F. L., et al. 2010. Cognitive behavioral guided self-help for the treatment of recurrent binge eating. Journal of Consulting and Clinical Psychology 78(3):312–321.

Lynch, F. L., et al. 2010. Cost-effectiveness of guided self-help treatment for recurrent binge eating. Journal of Consulting and Clinical Psychology 78(3):322–333.

Maine, M., B. H. McGilley, and D. Bunnell (Eds.). 2010. Treatment of Eating Disorders: Bridging the Research-Practice Gap. London: Academic Press.

Ogden, C. L., et al. 2012. Prevalence of obesity and trends in body mass index among US children and adolescents, 1999–2010. JAMA 307(5):483–490.

Healthy People

ACTIVITY

• Increase proportion of adults with healthy weight.

• Reduce childhood overweight and obesity.

• Reduce disorder eating among adolescents.

• Increase proportion of adults with high LDL who control weight and get activity.

• Reduce percentage of adults who do no leisure-time activity.

• Increase work sites that offer nutrition and weight man- agement classes and counseling.

• Increase physician counseling on nutrition and weight management.

• Increase BMI measurement by primary doctors.

• Increase policies that give retail food outlets incentives for foods that meet dietary guidelines.

A national goal is to increase the proportion of adults with a healthy

weight. More than twice as many adults are overweight or obese

than youth. However, studies show that overweight youth are more

likely to become overweight adults. Is it important to focus on

obesity prevention at all ages or should more concentrated efforts

be focused specifically on children to help prevent problems in the

future? What changes would you implement first to help reverse the

obesity epidemic in society?

cor22568_ch13_289-322.indd 304 10/09/12 7:34 PM

F O S T E R , C E D R I C 1 6 9 2 T S

L a

b R

e s o

u rc

M a

te ria

305

Calculating Fatness from Skinfolds

(FITNESSGRAM Method)

1. Sum the three skinfolds (triceps, abdominal, and calf) for men and women. Use horizontal abdominal measure.

2. Use the skinfold sum and the appropriate column (men or women) to determine your percent fat using Chart 1 . Locate your sum of skinfold in the left col- umn at the top of the chart. Your estimated body fat percentage is located where the values intersect.

3. Use the Standards for Body Fatness ( Chart 2 ) to determine your fatness rating.

FITNESSGRAM Locations

(Men and Women)

Triceps

Make a mark on the back of the right arm, one- half the distance between the tip of the shoulder and the tip of the elbow. Make the measurement at this location.

Abdominal

Make a mark on the skin approximately 1 inch to the right of the navel. Unlike the Jackson-Pollock method (done vertically), make a horizontal measurement.

VIDEO 6

General Information about

Skinfold Measurements

It is important to use a consistent procedure for “draw- ing up” or “pinching up” a skinfold and making the mea- surement with the calipers. The following procedures should be used for each skinfold site.

1. Lay the calipers down on a nearby table. Use the thumbs and index fingers of both hands to draw up a skinfold, or layer of skin and fat. The fingers and thumbs of the two hands should be about 1 inch apart, or 1/2 inch on each side of the location where the measurement is to be made.

2. The skinfolds are normally drawn up in a vertical line rather than a horizontal line. However, if the skin naturally aligns itself less than vertical, the measure- ment should be done on the natural line of the skin- fold, rather than on the vertical.

3. Do not pinch the skinfold too hard. Draw it up so that your thumbs and fingers are not compressing the skinfold.

4. Once the skinfold is drawn up, let go with your right hand and pick up the calipers. Open the jaws of the calipers and place them over the location of the skinfold to be measured and 1/2 inch from your left index finger and thumb. Allow the tips, or jaw faces, of the calipers to close on the skinfold at a level about where the skin would be normally.

5. Let the reading on the calipers settle for 2 or 3 seconds; then note the thickness of the skinfold in millimeters.

6. Three measurements should be taken at each loca- tion. Use the middle of the three values to deter- mine your measurement. For example, if you had values of 10, 11, and 9, your measurement for that location would be 10. If the three measures vary by more than 3 millimeters from the lowest to the high- est, you may want to take additional measurements.

Skinfold Measurement Methods

You will be exposed to two methods of using skinfolds. The first method (FITNESSGRAM) uses the same sites for men and women. It was originally developed for use with schoolchildren but has since been modified for adults. The second method (Jackson-Pollock) is the most widely used method. It uses different sites for men and women and considers your age in estimating your body fat per- centage. You are encouraged to try both methods.

Lab Resource Materials: Evaluating Body Fat

E va

lu a tin

g B

o d

y F a t

cor22568_ch13_289-322.indd 305 24/08/12 8:10 PM

F O S T E R , C E D R I C 1 6 9 2 T S

306

L a

b R

e s o

u rc

M a

te ri

a ls

Calf skinfold

Make a mark on the inside of the calf of the right leg at the level of the largest calf size (girth). Place the foot on a chair or other elevation so that the knee is kept at approximately 90 degrees. Make a vertical mea- surement at the mark.

Self-Measured Triceps Skinfold

This measurement is made on the left arm so that the calipers can easily be read. Hold the arm straight at shoulder height. Make a fist with the thumb faced upward. Place the fist against a wall. With the right hand, place the calipers over the skinfold as it “hangs freely” on the back of the tricep (halfway from the tip of the shoulder to the elbow).

Caliper

E va

lu a ti n g

B o

d y

F a t

FITNESSGRAM Locations (continued)

Men Women

Sum of

Skinfolds

Percent

Fat

Sum of

Skinfolds

Percent

Fat

8–10 3.2 23–25 16.8 11–13 4.1 26–28 17.7

14–46 5.0 29–31 18.5 17–19 6.0 32–34 19.4

20–22 6.0 35–37 20.2 23–25 7.8 38–40 21.0

26–28 8.7 41–43 21.9 29–31 9.7 44–46 22.7

32–34 10.6 47–49 23.5 35–37 11.5 50–52 24.4

38–40 12.5 53–55 25.2 41–43 13.4 56–58 26.1

44–46 14.3 59–61 26.9 47–49 15.2 62–64 27.7

50–52 16.2 65–67 28.6 53–55 17.1 68–70 29.4

56–58 18.0 71–73 30.2 59–61 18.9 74–76 31.1

62–64 19.9 77–79 31.9 65–67 20.8 80–82 32.7

68–70 21.7 83–85 33.6 71–73 22.6 86–88 34.4

74–76 23.6 89–91 35.5 77–79 24.5 92–94 36.1

80–82 25.4 95–97 36.9 83–85 26.4 98–100 37.8

86–88 27.3 101–103 38.6 89–91 28.2 104–106 39.4

92–94 29.1 107–109 40.3 95–97 30.1 110–112 41.1

98–100 31.0 113–115 42.0 101–103 31.9 116–118 42.8

104–106 32.8 119–121 43.6 107–109 33.8 122–124 44.5

110–112 34.7 125–127 45.3 113–115 35.6 128–130 46.1

116–118 36.6 131–133 47.0 119–121 37.5 134–136 47.8

122–124 38.4 137–139 48.7 125–127 39.3 140–142 49.5

Chart 1 Percent Fat for Sum of Triceps, Abdominal, and Calf Skinfolds (Fitnessgram)

(Healthy) (At Risk) Too Low Borderline Good Fitness Marginal Overfat

Below Essential Fat Levels

Unhealthy for Many People

Optimal for Good Health

Associated with Some Health Problems

Unhealthy

Males No less than 5% 6–9% 10–20% 21–25% >25%

Females No less than 10% 11–16% 17–28% 29–35% >35%

Chart 2 Standards for Body Fatness (Percent Body Fat)

cor22568_ch13_289-322.indd 306 24/08/12 8:10 PM

F O S T E R , C E D R I C 1 6 9 2 T S

L a

b R

e s o

u rc

M a

te ria

307

Jackson-Pollock Locations (Men)

Chest

Make a mark above and to the right of the right nipple (one-half the distance from the midline of the side and the nipple). The measurement at this location is often done on the diagonal because of the natu- ral line of the skin.

Abdominal

Make a mark on the skin approximately 1 inch to the right of the navel. Make a vertical measure for the Jackson- Pollock method and horizontally for the FITNESSGRAM method.

Thigh

Same as for women. Note: Research has identified other methods that can also be used to calculate body fatness using skinfold measurements. See below.

• Ball, S., Altena, T., and P. Swan. 2004. Accuracy of anthropometry compared to dual energy x-ray absorp- tiometry: A new generalizable equation for men. Euro- pean Journal of Clinical Nutrition 58:1525–1531.

• Ball, S., Swan, P., and R. Desimone. 2004. Compari- son of anthropometry compared to dual energy x-ray absorptiometry: A new generalizable equation for women. Research Quarterly for Exercise and Sports 75:248–258.

Calculating Fatness from Skinfolds

(Jackson-Pollock Method)

1. Sum three skinfolds (tricep, iliac crest, and thigh for women; chest, abdominal [vertical], and thigh for men).

2. Use the skinfold sum and your age to determine your percent fat using Chart 3 for women and Chart 4 for men. Locate your sum of skinfold in the left column and your age at the top of the chart. Your estimated body fat percentage is located where the values intersect.

3. Use the Standards for Body Fatness ( Chart 2 ) to determine your fatness rating.

Jackson-Pollock Locations (Women)

Triceps

Same as FITNESSGRAM (see page 305).

Iliac crest

Make a mark at the top front of the iliac crest. This skinfold is taken diagonally because of the natural line of the skin.

Thigh

Make a mark on the front of the thigh mid- way between the hip and the knee. Make the measurement vertically at this location.

E va

lu a tin

g B

o d

y F a t

cor22568_ch13_289-322.indd 307 24/08/12 8:10 PM

F O S T E R , C E D R I C 1 6 9 2 T S

308

L a

b R

e s o

u rc

M a

te ri

a ls

E va

lu a ti n g

B o

d y

F a t

Age to the Last Year

Sum of Skinfolds

(mm)

22 and

Under

23 to

28 to

33 to

38 to

43 to

48 to

53 to

Over

23–25 9.7 9.9 10.2 10.4 10.7 10.9 11.2 11.4 11.7 26–28 11.0 11.2 11.5 11.7 12.0 12.3 12.5 12.7 13.0

29–31 12.3 12.5 12.8 13.0 13.3 13.5 13.8 14.0 14.3 32–34 13.6 13.8 14.0 14.3 14.5 14.8 15.0 15.3 15.5

35–37 14.8 15.0 15.3 15.5 15.8 16.0 16.3 16.5 16.8 38–40 16.0 16.3 16.5 16.7 17.0 17.2 17.5 17.7 18.0

41–43 17.2 17.4 17.7 17.9 18.2 18.4 18.7 18.9 19.2 44–46 18.3 18.6 18.8 19.1 19.3 19.6 19.8 20.1 20.3

47–49 19.5 19.7 20.0 20.2 20.5 20.7 21.0 21.2 21.5 50–52 20.6 20.8 21.1 21.3 21.6 21.8 22.1 22.3 22.6

53–55 21.7 21.9 22.1 22.4 22.6 22.9 23.1 23.4 23.6 56–58 22.7 23.0 23.2 23.4 23.7 23.9 24.2 24.4 24.7

59–61 23.7 24.0 24.2 24.5 24.7 25.0 25.2 25.5 25.7 62–64 24.7 25.0 25.2 25.5 25.7 26.0 26.2 26.4 26.7

65–67 25.7 25.9 26.2 26.4 26.7 26.9 27.2 27.4 27.7 68–70 26.6 26.9 27.1 27.4 27.6 27.9 28.1 28.4 28.6

71–73 27.5 27.8 28.0 28.3 28.5 28.8 28.0 29.3 29.5 74–76 28.4 28.7 28.9 29.2 29.4 29.7 29.9 30.2 30.4

77–79 29.3 29.5 29.8 30.0 30.3 30.5 30.8 31.0 31.3 80–82 30.1 30.4 30.6 30.9 31.1 31.4 31.6 31.9 32.1

83–85 30.9 31.2 31.4 31.7 31.9 32.2 32.4 32.7 32.9 86–88 31.7 32.0 32.2 32.5 32.7 32.9 33.2 33.4 33.7

89–91 32.5 32.7 33.0 33.2 33.5 33.7 33.9 34.2 34.4 92–94 33.2 33.4 33.7 33.9 34.2 34.4 34.7 34.9 35.2

95–97 33.9 34.1 34.4 34.6 34.9 35.1 35.4 35.6 35.9 98–100 34.6 34.8 35.21 35.3 35.5 35.8 36.0 36.3 36.5

101–103 35.3 35.4 35.7 35.9 36.2 36.4 36.7 36.9 37.2 104–106 35.8 36.1 36.3 36.6 36.8 37.1 37.3 37.5 37.8

107–109 36.4 36.7 36.9 37.1 37.4 37.6 37.9 38.1 38.4 110–112 37.0 37.2 37.5 37.7 38.0 38.2 38.5 38.7 38.9

113–115 37.5 37.8 38.0 38.2 38.5 38.7 39.0 39.2 39.5 116–118 38.0 38.3 38.5 38.8 39.0 39.3 39.5 39.7 40.0

119–121 38.5 38.7 39.0 39.2 39.5 39.7 40.0 40.2 40.5 122–124 39.0 39.2 39.4 39.7 39.9 40.2 40.4 40.7 40.9

125–127 39.4 39.6 39.9 40.1 40.4 40.6 40.9 41.1 41.4 128–130 39.8 40.0 40.3 40.5 40.8 41.0 41.3 41.5 41.8

Source: Baumgartner and Jackson.

Note: Percent fat calculated by the formula by Siri. Percent fat = [(4.95/BD) – 4.5] × 100, where BD = body density.

Chart 3 Percent Fat for Women (Jackson-Pollock: Sum of Triceps, Iliac Crest, and Thigh Skinfolds)

cor22568_ch13_289-322.indd 308 24/08/12 8:10 PM

F O S T E R , C E D R I C 1 6 9 2 T S

L a

b R

e s o

u rc

M a

te ria

309

the triceps measure, use the self-measurement technique for men and women. (See page 306.)

2. Calculate fatness using the methods described previously.

Calculating Fatness from

Self-Measured Skinfolds

1. Use either the Jackson-Pollock or Fitnessgram method, but make the measures on yourself rather than have a partner do the measures. When doing

Chart 4 Percent Fat for Men (Jackson-Pollock: Sum of Thigh, Chest, and Abdominal Skinfolds)

Age to the Last Year

Sum of Skinfolds

(mm)

22 and

Under

23 to

28 to

33 to

38 to

43 to

48 to

53 to

Over

8–10 1.3 1.8 2.3 2.9 3.4 3.9 4.5 5.0 5.5 11–13 2.2 2.8 3.3 3.9 4.4 4.9 5.5 6.0 6.5

14–16 3.2 3.8 4.3 4.8 5.4 5.9 6.4 7.0 7.5 17–19 4.2 4.7 5.3 5.8 6.3 6.9 7.4 8.0 8.5

20–22 5.1 5.7 6.2 6.8 7.3 7.9 8.4 8.9 9.5 23–25 6.1 6.6 7.2 7.7 8.3 8.8 9.4 9.9 10.5

26–28 7.0 7.6 8.1 8.7 9.2 9.8 10.3 10.9 11.4 29–31 8.0 8.5 9.1 9.6 10.2 10.7 11.3 11.8 12.4

32–34 8.9 9.4 10.0 10.5 11.1 11.6 12.2 12.8 13.3 35–37 9.8 10.4 10.9 11.5 12.0 12.6 13.1 13.7 14.3

38–40 10.7 11.3 11.8 12.4 12.9 13.5 14.1 14.6 15.2 41–43 11.6 12.2 12.7 13.3 13.8 14.4 15.0 15.5 16.1

44–46 12.5 13.1 13.6 14.2 14.7 15.3 15.9 16.4 17.0 47–49 13.4 13.9 14.5 15.1 15.6 16.2 16.8 17.3 17.9

50–52 14.3 14.8 15.4 15.9 16.5 17.1 17.6 18.1 18.8 53–55 15.1 15.7 16.2 16.8 17.4 17.9 18.5 18.2 19.7

56–58 16.0 16.5 17.1 17.7 18.2 18.8 19.4 20.0 20.5 59–61 16.9 17.4 17.9 18.5 19.1 19.7 20.2 20.8 21.4

62–64 17.6 18.2 18.8 19.4 19.9 20.5 21.1 21.7 22.2 65–67 18.5 19.0 19.6 20.2 20.8 21.3 21.9 22.5 23.1

68–70 19.3 19.9 20.4 21.0 21.6 22.2 22.7 23.3 23.9 71–73 20.1 20.7 21.2 21.8 22.4 23.0 23.6 24.1 24.7

74–76 20.9 21.5 22.0 22.6 23.2 23.8 24.4 25.0 25.5 77–79 21.7 22.2 22.8 23.4 24.0 24.6 25.2 25.8 26.3

80–82 22.4 23.0 23.6 24.2 24.8 25.4 25.9 26.5 27.1 83–85 23.2 23.8 24.4 25.0 25.5 26.1 26.7 27.3 27.9

86–88 24.0 24.5 25.1 25.5 26.3 26.9 27.5 28.1 28.7 89–91 24.7 25.3 25.9 25.7 27.1 27.6 28.2 28.8 29.4

92–94 25.4 26.0 26.6 27.2 27.8 28.4 29.0 29.6 30.2 95–97 26.1 26.7 27.3 27.9 28.5 29.1 29.7 30.3 30.9

98–100 26.9 27.4 28.0 28.6 29.2 29.8 30.4 31.0 31.6 101–103 27.5 28.1 28.7 29.3 29.9 30.5 31.1 31.7 32.3

104–106 28.2 28.8 29.4 30.0 30.6 31.2 31.8 32.4 33.0 107–109 28.9 29.5 30.1 30.7 31.3 31.9 32.5 33.1 33.7

110–112 29.6 30.2 30.8 31.4 32.0 32.6 33.2 33.8 34.4 113–115 30.2 30.8 31.4 32.0 32.6 33.2 33.8 34.5 35.1

116–118 30.9 31.5 32.1 32.7 33.3 33.9 34.5 35.1 35.7 119–121 31.5 32.1 32.7 33.3 33.9 34.5 35.1 35.7 36.4

122–124 32.1 32.7 33.3 33.9 34.5 35.1 35.8 36.4 37.0 125–127 32.7 33.3 33.9 34.5 35.1 35.8 36.4 37.0 37.6

Source: Baumgartner and Jackson.

Note: Percent fat calculated by the formula by Siri. Percent fat = [(4.95/BD) – 4.5] × 100, where BD = body density.

E va

lu a tin

g B

o d

y F a t

cor22568_ch13_289-322.indd 309 24/08/12 8:10 PM

F O S T E R , C E D R I C 1 6 9 2 T S

310

L a

b R

e s o

u rc

M a

te ri

a ls

Height-Weight Measurements

1. Height —Measure your height in inches or centime- ters. Take the measurement without shoes, but add 2.5 centimeters or 1 inch to measurements, as the charts include heel height.

2. Weight —Measure your weight in pounds or kilograms without clothes. Add 3 pounds or 1.4 kilograms because the charts include the weight of clothes. If weight must be taken with clothes on, wear indoor clothing that weighs 3 pounds, or 1.4 kilograms.

3. Determine your frame size using the elbow breadth. The measurement is most accurate when done with a broad-based sliding caliper. However, it can be done using skinfold calipers or can be estimated with a metric ruler. The right arm is measured when it is elevated with the elbow bent at 90 degrees and the upper arm horizontal. The back of the hand should face the person making the measurement. Using the calipers, measure the distance between the epicondyles of the humerus (inside and outside bony points of the elbow). Measure to the nearest millimeter (1/10 centimeter). If a caliper is not avail- able, place the thumb and the index finger of the left hand on the epicondyles of the humerus and measure the distance between the fingers with a metric ruler. Use your height and elbow breadth in centimeters to determine your frame size ( Chart 5 ); you need not repeat this procedure each time you use a height and weight chart.

E va

lu a ti n g

B o

d y

F a t

Chart 5 Frame Size Determined from Elbow Breadth (mm)

Elbow Breadth (mm)

Height

Small

Frame

Medium

Frame

Large

Frame

Males

5’2 1/2” or less

<64 64–72 >72

5´3˝–5´6 ½˝ <67 67–74 >74

5´7˝–5´10 ½˝ <69 69–76 >76

5´11˝–6´2 ½˝ <71 71–78 >78

6´3˝ or more <74 74–81 >81

Females

4´10 ½˝ or less <56 56–64 >64

4´11˝–5´2 ½˝ <58 58–65 >65

5´3˝–5´6 ½˝ <59 59–66 >66

5´7˝–5´10 ½˝ <61 61–68 >69

5´11˝ or more <62 62–69 >69

Source: Metropolitan Life Insurance Company.

Height is given including 1-inch heels.

Chart 6 Healthy Weight Ranges for Adult Women and Men

Height Height

Feet Inches Pounds Feet Inches Pounds

4 10 91–119 5 9 129–169

4 11 94–124 5 10 132–174

5 0 97–128 5 11 136–179

5 1 101–132 6 0 140–184

5 2 104–137 6 1 144–189

5 3 107–141 6 2 148–195

5 4 111–146 6 3 152–200

5 5 114–150 6 4 156–205

5 6 118–155 6 5 160–211

5 7 121–160 6 6 164–216

5 8 125–164

Source: U.S. Department of Agriculture and Department of Health and Human Services.

4. Use Chart 6 to determine your healthy weight range. The new healthy weight range charts do not account for frame size. However, you may want to consider frame size when determining a personal weight within the healthy weight range. People with a larger frame size typically can carry more weight within the range than can those with a smaller frame size.

cor22568_ch13_289-322.indd 310 24/08/12 8:10 PM

F O S T E R , C E D R I C 1 6 9 2 T S

L a

b R

e s o

u rc

M a

te ria

311

Formula

Determining the Waist-to-Hip Circumference Ratio

The waist-to-hip circumference ratio is recommended as the best available index for determining risk for dis- ease associated with fat and weight distribution. Disease and death risk are associated with abdominal and upper body fatness. When a person has high fatness and a high waist-to-hip ratio, additional risks exist. The following steps should be taken in making measurements and cal- culating the waist-to-hip ratio.

1. Both measurements should be done with a nonelas- tic tape. Make the measurements while standing with the feet together and the arms at the sides, elevated only high enough to allow the measurements. Be sure the tape is horizontal and around the entire cir- cumference. Record scores to the nearest millimeter or 1/16th of an inch. Use the same units of measure for both circumferences (millimeters or 1/16th of an inch). The tape should be pulled snugly but not to the point of causing an indentation in the skin.

BMI = weight in kilograms (kg)

(height in meters) × (height in meters)

BMI = weight in pounds (lb)

(height in inches) × (height in inches)

Body Mass Index (BMI)

Use the steps listed below or use Chart 7 to calculate your BMI.

1. Divide your weight in pounds by 2.2 to determine your weight in kilograms.

2. Multiply your height in inches by 0.0254 to deter- mine your height in meters.

3. Square your height in meters (multiply your height in meters by your height in meters).

4. Divide your weight in kilograms from step 1 by your height in meters squared from step 3.

5. If you use these steps to determine your BMI, use the Rating Scale for Body Mass Index ( Chart 8 ) to obtain a rating for your BMI.

Chart 7 Body Mass Index (BMI)

5'0" 5'1" 5'2" 5'3" 5'4" 5'5" 5'6" 5'7" 5'8" 5'9" 5'10" 5'11" 6'0" 6'1" 6'2" 6'3" 6'4"

H ei

gh t

Weight

20 21 21 22 23 24 19 20 21 22 23 24 18 19 20 21 22 23 18 17 17 16 16 15

16 16

15 16 16 14 15

15 16

14 14 14 13 14

15 16 15 16 16

1515 16 16 13 13 1514 15 12 13 12 13 13

1414 15 14 15

16 16 16 15 16 16

17 17 17 17

17 17

19 19 20 21 22 24

18 19 20 21 21 22 23 24 17 18 19

18 19 18 19

19 20 21 22 22 23 24

20 20 20

21 22 23 23 24 21

18 18 18

19 20 21 21 22 23 23 24

22 23 24 24 19

18 19 18 19

18 18 19 20

21 19 20

20 21 21 22

22 23 24 24 22 23 24 24

20 21 22 22 23 24 24 20 21 22 22 23 24 24

18 18 19 18 19 19

20 20 21 20 21 21

22 22 23 24 24 22 22 23 24 24

18 18

19 19 20 21 21 22 22 23 24 24 18 19 19 20 21 21 22 23 23 24 24

25 26 25 26

27 28 29 30 31 32 33 34 35

31 32 33 32

3232 33 34 35

33 34 35 35

36 37

34 35 36 37

31 32 33 34 35 36 37 37

38 39

3936 37 38 39 33 34 35 36

3636 3737 38 39

37 38 3838

40 41 42 43

36 37 38 39 40 41

41 41

42 43 43

44 45

38 39 40 41 42 43 44 45

46 31 32 33 34 35 36 37 38 39 40 41 42 43 43 44 45 46

47 48 49 26 27 28 29

25 26 27 27 28 29 30

30 25 26 27 27 28 29 30

25 26 27 27 28 29 30 25 26 27 27 28 29 30

25 26 27 27 28 29 30

28 29 30

25 26 27 27 28 29 25 26

25 25

26 26 27 27 28 29

30 30 30

29 30 27 28

26 26 27 28 28 29 30 3026 26 27 28

28 29 30 3026 26 27 28 28 2929 3026 26 27 27

28 2929 30 30 3131

31 31

31 32 32

32 32 33 3333 34

31 31

3131 31

31 31

31 32 3232

3232

33 33

33 34 3434

33 32

32 31 32

33 34

35 35

35 33 34

33 34 35

35 36

36 37 3636 37 38

4040 40

40 42

42 43 44 46 47

26 26 27 27 100 105 110 115 120 125 130 135 140 145 150 155 160 165 170 175 180 185 190 195 200 205 230 240235 245 250210 215 220 225

29 29 30

23 24

5'0" 5'1" 5'2" 5'3" 5'4" 5'5" 5'6" 5'7" 5'8" 5'9" 5'10" 5'11" 6'0" 6'1" 6'2" 6'3" 6'4"

20 21 21 22 23 24 19 20 21 22 23 24 18 19 20 21 22 23 18 17 17 16 16 15

16 16

15 16 16

Low

14 15 15

16 14 14 14 13 14

15 16 15 16 16

1515 16 16 13 13 1514 15 12 13 12 13 13

1414 15 14 15

16 16 16 15 16 16

17 17 17 17

17 17

Normal (good fitness zone)

17 17

19 19 20 21 22 24

18 19 20 21 21 22 23 24 17 18 19

18 19 18 19

19 20 21 22 22 23 24

20 20 20

21 22 23 23 24 21

18 18 18

19 20 21 21 22 23 23 24

22 23 24 24 19

18 19 18 19

18 18 19 20

21 19 20

20 21 21 22

22 23 24 24 22 23 24 24

20 21 22 22 23 24 24 20 21 22 22 23 24 24

18 18 19 18 19 19

20 20 21 20 21 21

22 22 23 24 24 22 22 23 24 24

18 18

19 19 20 21 21 22 22 23 24 24 18 19 19 20 21 21 22 23 23 24 24

25 26 25 26

27 28 29 30 31 32 33 34 35

31 32 33 32

3232 33 34 35

33 34 35 35

36 37

34 35 36 37

31 32 33 34 35 36 37 37

38 39

3936 37 38 39 33 34 35 36

3636 3737 38 39

37 38 3838

40 41 42 43

36 37 38 39 40 41

41 41

42 43 43

44 45

38 39 40 41 42 43 44 45

46 31 32 33 34 35 36 37 38 39 40 41 42 43 43 44 45 46

47 48 49 26 27 28 29

25 26 27 27 28 29 30

30 25 26 27 27 28 29 30

25 26 27 27 28 29 30 25 26 27 27 28 29 30

25 26 27 27 28 29 30

28 29 30

25 26 27 27 28 29 25 26

25 25

26 26 27 27 28 29

30 30 30

29 30 27 28

26 26 27 28 28 29 30 3026 26 27 28

28 29

Obese

3026 26 27

Overweight

28 2929 3026 26 27 27 28 2929 30 30

3131 31

31 31 31

31 32 32

32 32 33 3333 34

31 31

3131 31

31 31

31 32 3232

3232

33 33

33 34 3434

33 32

32 31 32

33 34

35 35

35 33 34

33 34 35

35 36

36 37 3636 37 38

4040 40

40 42

42 43 44 46 47

26 26 27 27 100 105 110 115 120 125 130 135 140 145 150 155 160 165 170 175 180 185 190 195 200 205 230 240235 245 250210 215 220 225

29 29 30

23 24

Chart 8 Rating Scale for Body Mass Index (BMI)

Classification BMI

Obese (high risk) Over 30

Overweight 25–30

Normal (good fitness zone) 17–24.9

Low Less than 17

Note: An excessively low BMI is not desirable. Low BMI values can indi- cate eating disorders and other health problems.

E va

lu a tin

g B

o d

y F a t

× 703

cor22568_ch13_289-322.indd 311 24/08/12 8:10 PM

F O S T E R , C E D R I C 1 6 9 2 T S

312

L a

b R

e s o

u rc

M a

te ri

a ls

Note: Using a partner or mirror will aid you in keeping the tape horizontal.

Determining Disease Risk Based

on BMI and Waist Circumference

Use Chart 11 to determine a BMI and Waist Circumfer- ence Rating. In the first column of Chart 11 , locate your BMI. Locate your Waist Circumference in either column 2 or 3 depending on your age. Your rating is located at the point where the appropriate rows and columns intersect.

2. Waist measurement —Measure at the natural waist (smallest waist circumference). If no natural waist exists, the measurement should be made at the level of the umbilicus. Measure at the end of a nor- mal inhale.

3. Hip measurement —Measure at the maximum cir- cumference of the buttocks. It is recommended that you wear thin-layered clothing (such as a swimming suit or underwear) that will not add significantly to the measurement.

4. Divide the hip measurement into the waist measure- ment or use the waist-to-hip nomogram ( Chart 9 ) to determine your waist-to-hip ratio.

5. Use the Waist-to-Hip Ratio Rating Scale ( Chart 10 ) to determine your rating for the waist-to-hip ratio.

Chart 9 Waist-to-Hip Ratio Nomogram

Chart 10 Waist-to-Hip Ratio Rating Scale

Classification Men Women

High risk >1.0 >0.85

Moderately high risk 0.90–1.0 0.80–0.85

Lower risk <0.90 <0.80

Chart 11 BMI and Waist Circumference Rating Scale

Waist Circumference (in.)

BMI

Men 40 or less

Women 34.5 or

less

Men above 40

Women above

34.5

Less than 18.5 Normal Normal

18.5–24.9 Normal Normal

25.0–29.9 Increased risk High risk

30.0–34.9 High risk Very high risk

35.0–39.9 Very high risk Very high risk

40 or more Extremely high risk Extremely high risk

Source: Adapted from ACSM.

E va

lu a ti n g

B o

d y

F a t

cor22568_ch13_289-322.indd 312 10/09/12 7:34 PM

F O S T E R , C E D R I C 1 6 9 2 T S

313

L a

b 1

3 A

E va

lu a tin

g B

o d

y C o

m p

o sitio

n : S

kin fo

ld M

e a su

re s

Lab 13A Evaluating Body Composition: Skinfold Measures

Name Section Date

Purpose: To estimate body fatness using two skinfold procedures; to compare measures made by an expert, by a partner, and by self-measurements; to learn the strengths and weaknesses of each technique; and to use the results to establish personal standards for evaluating body composition

General Procedures: Follow the specifi c procedures for the two self-assessment techniques. If possible, have one set of measurements made by an expert (instructor) for each of the two techniques. Next, work with a partner you trust. Have the partner make measurements at each site for both techniques. Finally, make self-measurements for each of the sites. If you are just learning a measurement technique, it is important to practice the skills of making the measurement. If you do measurements over time, use the same instrument (if possible) each time you measure. If your measurements vary widely, take more than one set until you get more consistent results.

If you have had an underwater weighing, a bioelectric impedance measurement, a near-infrared interactance measure, or some other body fatness measurement done recently, record your results below.

Measurement Technique % Body Fat Rating

Skinfold Measurements (Jackson-Pollock Method)

Procedures for Jackson-Pollock Method

1. Read the directions for the Jackson-Pollock method measurements in Lab Resource Materials. 2. If possible, observe a demonstration of the proper procedures for measuring skinfolds at each of the different

locations before doing partner or self-measurements. 3. Make expert, partner, and self-measurements (see Lab Resource Materials). When doing the self-measure of the

triceps, use the self-measurement technique described in Lab Resource Materials (women only). 4. Record each of the measurements in the Results section. 5. Calculate your body fatness from skinfolds by summing the appropriate skinfold values (chest, thigh, and abdomi-

nal for men; triceps, iliac crest, and thigh for women). Using your age and the sum of the appropriate skinfolds, determine your body fatness using Charts 3 and 4 in Lab Resource Materials.

6. Rate your fatness using Chart 2 in Lab Resource Materials.

cor22568_ch13_289-322.indd 313 11/09/12 5:05 PM

F O S T E R , C E D R I C 1 6 9 2 T S

314

E va

lu a ti n g

B o

d y

C o

m p

o si

ti o

n :

S ki

n fo

ld M

e a su

re s

L a

b 1

3 A

Results for Jackson-Pollock Method

Skinfolds by an Expert (If Possible) Skinfolds by Partner Self-Measurements

Male Male Male

Chest Chest Chest

Thigh Thigh Thigh

Abdominal Abdominal Abdominal

Sum Sum Sum

% body fat % body fat % body fat

Rating Rating Rating

Female Female Female

Triceps Triceps Triceps

Iliac crest Iliac crest Iliac crest

Thigh Thigh Thigh

Sum Sum Sum

% body fat % body fat % body fat

Rating Rating Rating

Make a check by the statements that are true about your measurements.

The person doing measurements has experience with these three skinfold measurements.

Self-measurements were practiced until measurements became consistent.

Results of several trials for each measure are consistent (do not vary more than 2–3 mm).

You are not exceptionally low or exceptionally high in body fat.

The more checks you have, the more likely your measurements are accurate.

cor22568_ch13_289-322.indd 314 24/08/12 8:10 PM

F O S T E R , C E D R I C 1 6 9 2 T S

315

L a

b 1

3 A

Skinfold Measurements (FITNESSGRAM Method)

Procedures for FITNESSGRAM Method

1. Read the directions for the FITNESSGRAM measurements in Lab Resource Materials. 2. Use the procedures as for the FITNESSGRAM method using the triceps, abdominal, and calf sites described in Lab

Resource Materials. When doing the self-measure of the triceps, use the self-measurement technique shown earlier. 3. Calculate your body fatness from skinfolds by summing the appropriate skinfold values (same for both men and

women). Using the sum of the appropriate skinfolds, determine your body fatness using Chart 1 in Lab Resource Materials.

4. Rate your fatness using Chart 2 in Lab Resource Materials.

Results for FITNESSGRAM Method

Skinfolds by

an Expert (If Possible) Skinfolds by Partner Self-Measurements

Triceps Triceps Triceps

Abdominal Abdominal Abdominal

Calf Calf Calf

Sum Sum Sum

% body fat % body fat % body fat

Rating Rating Rating

Make a check by the statements that are true about your measurements.

The person doing measurements has experience with these three skinfold measurements.

Self-measurements were practiced until measurements became consistent.

Results of several trials for each measure are consistent (do not vary more than 2 to 3 mm).

You are not exceptionally low or exceptionally high in body fat.

The more checks you have, the more likely your measurements are accurate.

E va

lu a tin

g B

o d

y C o

m p

o sitio

n : S

kin fo

ld M

e a su

re s

cor22568_ch13_289-322.indd 315 11/09/12 5:05 PM

F O S T E R , C E D R I C 1 6 9 2 T S

316

L a

b 1

3 A

Conclusions and Implications

In the space provided below, discuss your current body composition based on the two skinfold procedures and any other measures of body fatness you did. Note any discrepancies in the measurements and discuss which of the measurements you think provide the most useful information. To what extent do you think you need to alter your level of body fatness?

E va

lu a ti n g

B o

d y

C o

m p

o si

ti o

n :

S ki

n fo

ld M

e a su

re s

cor22568_ch13_289-322.indd 316 24/08/12 8:10 PM

F O S T E R , C E D R I C 1 6 9 2 T S

317

L a

b 1

3 B

Lab 13B Evaluating Body Composition: Height, Weight, and Circumference Measures

Name Section Date

Purpose: To assess body composition using a variety of procedures, to learn the strengths and weaknesses of each technique, and to use the results to establish personal standards for evaluating body composition

General Procedures: Follow the specifi c procedures for the three self-assessment techniques. If possible, work with a partner you trust to help with measurements that you have diffi culty making yourself. If you are just learning a measurement technique, it is important to practice the skills of making the measurement. If you do measurements over time, use the same instrument (if possible) each time you measure. If your measurements vary widely, take more than one set until you get more consistent results. If possible, have an expert make measurements on you using these procedures.

Height and Weight Measurements

Procedures

1. Read the directions for height and weight measurements in Lab Resource Materials. 2. Determine your healthy weight range using Chart 6 in Lab Resource Materials. You may want to use your elbow

breadth (Chart 5). People with a smaller frame size should typically weigh less than those with a larger frame size within the healthy weight range. You may need the assistance of a partner to make the elbow breadth measurement.

3. Record your scores in the Results section.

Results

Weight Healthy weight range

Height

Make a check by the statements that are true about your measurements.

You are confident in the accuracy of the scale you used.

You are confident that the height technique is accurate.

The more checks you have, the more likely your measurements are accurate. If you are a very active person with a high amount of muscle, use this method with caution.

Body Mass Index

Procedures

1. Use the height and weight measures from above. 2. Determine your BMI score by using Chart 7 or the directions in Lab Resource Materials. Determine your rating

using Chart 8. 3. Record your score and rating in the Results section.

Results

Body mass index Rating

If you are a very active person with a high amount of muscle, use this method with caution.

E va

lu a tin

g B

o d

y C o

m p

o sitio

n : H

e ig

h t, W

e ig

h t, a

n d

C irc

u m

fe re

n c e M

e a su

re s

cor22568_ch13_289-322.indd 317 24/08/12 8:10 PM

F O S T E R , C E D R I C 1 6 9 2 T S

318

L a

b 1

3 B

Waist-to-Hip Ratio

Procedures

1. Measure your waist and hip circumferences using the procedures in Lab Resource Materials. 2. Divide your hip circumference into your waist circumference, or use Chart 9 in Lab Resource Materials to calculate

your waist-to-hip ratio. 3. Determine your rating using Chart 10 in Lab Resource Materials. 4. Record your scores in the Results section.

Results

Waist circumference Hip circumference Waist-to-hip ratio Rating

Make a check by the statements that are true about you.

I am a male 5´9˝ or less and have a waist girth of 34 inches or more.

I am a male 5´10˝ to 6´4˝ and have a waist girth of 36 inches or more.

I am a male 6´5˝ or more and have a waist girth of 38 inches or more.

I am a female 5´2˝ or less and have a waist girth of 29 inches or more.

I am a female 5´3˝ to 5´10˝ and have a waist girth of 31 inches or more.

I am a female 5´11˝ or more and have a waist girth of 33 inches or more.

If you checked one of the boxes above, the waist-to-hip ratio is especially relevant for you.

BMI and Waist Circumference Rating

Procedures

1. Locate your BMI and Waist Circumference from previous Results sections in this Lab. 2. Use these values to calculate your BMI and Waist Circumference Rating using Chart 11. Record the rating

in the Results section.

Results

BMI and Waist Circumference Rating

Conclusions and Implications

In the space below, discuss your results for the height, weight, and circumference procedures. Note any discrepancies in the measurements. Indicate the strengths and weaknesses of the various methods. Which of the measures do you think provided you with the most useful information? If you also did the skinfold measures (Lab 13A), discuss your body composition based on all the information you have collected (skinfolds and height, weight, and circumference measures).

E va

lu a ti n g

B o

d y

C o

m p

o si

ti o

n :

H e ig

h t,

W e ig

h t,

a n d

C ir c u m

fe re

n c e M

e a su

re s

cor22568_ch13_289-322.indd 318 24/08/12 8:10 PM

F O S T E R , C E D R I C 1 6 9 2 T S

319

L a

b 1

3 C

Lab 13C Determining Your Daily Energy Expenditure

Name Section Date

Purpose: To learn how many calories you expend in a day

Procedures

1. Estimate your basal metabolism using step 1 in the Results section in this Lab. First determine the number of minutes you sleep.

2. Monitor your activity expenditure for 1 day using Chart 1 (page 321). Record the number of 5-, 15-, and 30-minute blocks of time you perform each of the different types of physical activities (e.g., if an activity lasted 20 minutes, you would use one 15-minute block and one 5-minute block). Be sure to distinguish between moderate (Mod) and vigorous (Vig) intensity in your logging. If you perform an activity that is not listed, specify the activity on the line labeled “Other” and estimate if it is moderate or vigorous. You may want to keep copies of Chart 1 for future use. One extra copy is provided on page 322.

3. Sum the total number of minutes of moderate and vigorous activity. Determine your calories expended during mod- erate and vigorous activity using steps 2 and 3.

4. Determine your nonactive minutes using step 4. This is all time that is not spent sleeping or being active. 5. Determine your calories expended in nonactive minutes using step 5. 6. Determine your calories expended in a day using step 6.

Results

Daily Caloric Expenditure Estimates

Step 1: Basal calories

Body wt. (lbs.) Minutes of sleep Basal calories

= .0076 × × = (A)

Step 2: Calories (moderate activity)

Body wt. (lbs.) Minutes of moderate activity

Calories in moderate activity

= .036 × × = (B)

Step 3: Calories (vigorous activity)

Body wt. (lbs.) Minutes of vigorous activity

Calories in vigorous activity

= .053 × × = (C)

Step 4: Minutes (nonactive)

Minutes of sleep

Minutes of moderate activity

Minutes of vigorous activity

= 1,440 min – – – =

Nonactive minutes

Step 6: Calories expended (per day)

(A) (B) (C)

= =+ ++

(D) Daily calories

Step 5: Calories (rest and light activity)

Body wt. (lbs.) Nonactive minutes Calories in other activities

= .011 × × = (D)

D e te

rm in

in g

Y o

u r D

a ily E

n e rg

y E xp

e n d

itu re

cor22568_ch13_289-322.indd 319 24/08/12 8:10 PM

F O S T E R , C E D R I C 1 6 9 2 T S

320

L a

b 1

3 C

Answer the following questions about your daily caloric expenditure estimate.

Yes No

Were the activities you performed similar to what you normally perform each day?

Do you think your daily estimated caloric expenditure is an accurate estimate?

Do you think you expend the correct number of calories in a typical day to maintain the body composition (body fat level) that is desirable for you?

Conclusions and Interpretations: In several paragraphs, discuss your daily caloric expenditure. Comment on your answers to the preceding questions. In addition, comment on whether you think you should modify your daily caloric expenditure for any reason.

D e te

rm in

in g

Y o

u r

D a ily

E n e rg

y E

xp e n d

it u re

cor22568_ch13_289-322.indd 320 24/08/12 8:10 PM

F O S T E R , C E D R I C 1 6 9 2 T S

321

L a

b 1

3 C

Chart 1 Daily Activity Log

Day of Monitoring:

Physical Activity Category

Lifestyle Activity

Dancing (general) Gardening Home repair/maintenance Occupation

Mod Mod Mod Mod

5 Minutes Minutes

Walking/hiking Mod Other: Mod

1 62 543

15 Minutes

1 62 543

30 Minutes

1 2 3

Aerobic Activity 1 62 543 1 62 543 1 2 3

Sport/Recreation Activity 1 62 543 1 62 543 1 2 3

Flexibility Activity 1 62 543 1 62 543 1 2 3

Strengthening Activity 1 62 543 1 62 543 1 2 3

Aerobic dance (low-impact) Mod Vig

Vig Basketball Mod

Vig

Bowling/billiards Mod Golf Mod Martial arts (judo, karate) Mod

Vig Racquetball/tennis Mod

Stretching Mod Other: Mod

Resistance exercise Mod Other: Mod

Minutes of moderate activity

Minutes of vigorous activity

Total minutes of activity

Calisthenics (push-ups/sit-ups) Mod

Vig

Soccer/hockey Mod

Softball/baseball Mod Volleyball Mod

Aerobic machines (rowing, stair, ski)

Mod Vig

Bicycling Mod Vig

Running Mod Vig

Skating (roller/ice) Mod Vig

Swimming (laps) Mod Vig

Other: Mod Vig

Other: Mod

D e te

rm in

in g

Y o

u r D

a ily E

n e rg

y E xp

e n d

itu re

cor22568_ch13_289-322.indd 321 24/08/12 8:10 PM

F O S T E R , C E D R I C 1 6 9 2 T S

322

L a

b 1

3 C

Chart 1 Daily Activity Log

Day of Monitoring:

Physical Activity Category

Lifestyle Activity

Dancing (general) Gardening Home repair/maintenance Occupation

Mod Mod Mod Mod

5 Minutes Minutes

Walking/hiking Mod Other: Mod

1 62 543

15 Minutes

1 62 543

30 Minutes

1 2 3

Aerobic Activity 1 62 543 1 62 543 1 2 3

Sport/Recreation Activity 1 62 543 1 62 543 1 2 3

Flexibility Activity 1 62 543 1 62 543 1 2 3

Strengthening Activity 1 62 543 1 62 543 1 2 3

Aerobic dance (low-impact) Mod Vig

Vig Basketball Mod

Vig

Bowling/billiards Mod Golf Mod Martial arts (judo, karate) Mod

Vig Racquetball/tennis Mod

Stretching Mod Other: Mod

Resistance exercise Mod Other: Mod

Minutes of moderate activity

Minutes of vigorous activity

Total minutes of activity

Calisthenics (push-ups/sit-ups) Mod

Vig

Soccer/hockey Mod

Softball/baseball Mod Volleyball Mod

Aerobic machines (rowing, stair, ski)

Mod Vig

Bicycling Mod Vig

Running Mod Vig

Skating (roller/ice) Mod Vig

Swimming (laps) Mod Vig

Other: Mod Vig

Other: Mod

D e te

rm in

in g

Y o

u r

D a ily

E n e rg

y E

xp e n d

it u re

cor22568_ch13_289-322.indd 322 24/08/12 8:10 PM

F O S T E R , C E D R I C 1 6 9 2 T S

read (2)
read (3)

9780078022562_ch10_199-224_print
9780078022562_ch11_225-264_print

read (4)