Anthropometric and body composition lab QAs

EXS 31600 Exercise Physiology Laboratory

Lab 1

Objectives

• Know the range of values for percent body fat considered typical for college aged men and women

• Know the body mass index (BMI) values that indicate obesity for men and women

• Competently perform BMI, circumference, skinfold, and Bioeletrical Impedance Analysis (BIA) measurements

• Calculate body density and percent body fat based on the two- component body composition system

• Describe common sources of error in body composition measurements

• Know the rationale and important factors of body composition measurments

Definitions

• Body mass index (BMI): ratio of an individual's weight (kg) to height squared (m2)

• Densitometry: measurement of body density (Dbody = Massbody/Volumebody)

• Fat-free mass (FFM): all body tissue that is not fat, including bone, muscle, organ, and connective tissue; synonymous with lean body mass (LBM). Exepressed as a unit of weight (kg)

• Relative body fat: amount of body fat expressed as a percentage of total body weight

Definitions

• Skinfold caliper: instrument used to measure the thickness of pinched skinfolds; must provide a standard pinch pressure in order to provide accurate values

• Skinfold thickness: body composition measurement using the thickness of skinfolds, and thus subcutaneous fat, as an estimate of body density;

• Two-component body composition: commonly used system in which the body is assumed to have two major components: fat and fat-free (or lean) tissue.

Background

• Body composition: refers to the components that make up the body • Generally only interested in the percentage of the body that is adipose (or fat)

tissue vs. the percentage that is fat free

• Why? • Obesity – overfatness is closely related to a number of health risks

• CVD

• Peripheral vascular disease

• Hypertension

• Diabetes

• Other reasons • Athlete wishing to maximize their performance by optimizing their amount of

muscle and fat

Background

• Important to know body weight, weight that is fat, and weight that is fat free

• There are a variety of different techniques to measure body composition

• Only cover in this lab: • Anthropometry

• BMI

• BIA

• Skinfold thickness

Background

• Some body fat is necessary for: • Cellular mechanisms, Vitamins, Hormones, and Schwann cells

• Essential fat: thought to make up 3% of body weight in men and 12% in women

• Non-essential fat (storage fat): used for fuel but people’s main interest is to decrease it for health, athletic performance, or vanity

• Different classifications exists for relative body fat • Based on sex and age

Relative Body Fat Classifications

Body Composition Models

• Several models exists

• 2-component model • Fat mass

• Fat free mass • protein, water, and bone

• Multicomponent models are considered more accurate as they remove some assumptions compared to the 2-component model

Body Composition Models

• 2-component model • Assumed to have consistent densities within a certain population or

age group • For example,

• Fat mass in white adults, the density is 0.90 g・ml-1

• Fat free mass in white adults, the density is 1.1 g・ml-1

• Siri used these values to derive an equation to estimate percent body fat in adult white males

• %BF = [(4.95 / Db) − 4.50] x 100 (Siri, 1961)

• Slight variances in lean mass (FFM) densities • Different equations exist

• Age, sex, race

BMI for Categorizing Body Composition

• BMI = Wt (kg) / Ht2 (m2)

• Rationale • The weight-to-height ratios across the general population have a

positive relationship with percent body fat • Obesity is associated with a threefold greater risk of diabetes and

hypertension

• Limitation • Does not separate how much weight is fat or lean body mass • Can cause false classification

• BMI can be an indicator of high body fatness, however it is used as a screening tool not an actual measurement of body fatness.

BMI Classification

Circumference Measurements

• Waist-to-hip ratio (W:H) • A simple measurement associated with increased health risk

• Waist • narrowest part of the torso

• Hip • maximum extension of the buttocks

• Increased W:H ratio • Increases the risk for heart attack, stroke, hypertension, diabetes,

gallbladder disease, and death

Waist-to-Hip Ratio Classification

Skinfold Thickness As A Measure of Body Fat

• Quite common to estimate body fat based on skinfold thickness • Due to relative ease of measurement with minimal equipment

• Still need practice though!

• Skinfold calipers • Cheap, plastic are inaccurate

• Does not exert constant pressure

• Lange calipers • Exert constant pressure

• Expensive

Skinfold Thickness As A Measure of Body Fat

• Rationale for skinfold thickness • Age-dependent proportion of body

fat is deposited subcutaneously • Measuring the amount of adipose

tissue that can be pinched provides some indication of the amount of overall body fat

• Different equations based on the number of sites, specific race, age, and sex

• Skinfold measures has an error of ~3.5%

Bioelectrical Impedance Analysis (BIA)

• BIA is based on the principle that lean tissue conducts electrical current better than fat tissue

• More muscle = faster conduction • More fat = slower conduction

• Low-level electrical current is passed through the body and impedance is determined by the analyzer

• BIA can also estimate total body water that is proportional to the amount of lean tissue

• Different devices for home use • Tanita (foot-to-foot) • Omron (hand-to-hand)

Bioelectrical Impedance Analysis

Measures between Right and Left legs Measures between Right and Left arms

BIA Pre-Test Guidelines

• No eating or dinking for 4 h prior to test

• No exercise for 12 h prior to test

• No alcohol consumption for 48 h to test

• No diuretic medications • No caffeine

• Can postpone test if retaining water • Females (menstrual cycle)

Procedures And Sources of Error for Lab 1 Measurements

Height • Stadiometer

• Measure to the nearest centimeter

• E.g. 177.6 cm

• Things to consider • “Compress” the

participant’s hair may be necessary

• Removal of shoes

• Hair should be worn down

Photo via.

tigermedical.com

Height Procedure

1. Person must stand away from the stadiometer.

2. Straight facing with head in a horizontal position, shoulders back and heels together (60°)

3. Participant inhales deeply and maintains the position

4. Read the measurement before asking the subject to step off.

Weight

• Weight scale

• Measure to the nearest kilogram

• E.g. 83.6 kg

Photo via. tigermedical.com

Weight Procedure

1. Use a platform scale, physician’s scale or a digital scale.

2. Shoes must be off and everything out of pockets

3. Person stands on and faces the scale

4. Adjust the heavy and light beam, until the pointer is midair within the window of the scale (Physician scale)

5. If using a electronic digital scale, technician reads value indicated on the display

Heart Rate (HR) Procedure

• Unit: beats per minute (bpm)

• Palpate using the index and middle fingers

• Taking HR manually using the radial artery

• 6 seconds, multiply by 10

• 15 seconds, multiply by 4

• 30 seconds, multiply by 2

• Remember, the less time you count, the less accurate your measure will be

Photo via. Polarusa.com

Blood Pressure

• Measured on the brachial artery.

• Unit of measure is mm Hg (millimeter of mercury)

• Korotkoff Sounds • The sounds made by the vibration from the

vascular walls due to increased pressure.

• Phase 1: systolic pressure, the first sound you hear after the pressure is released from the BP cuff.

• As the pressure is decreased the sounds get softer

• Phase 5: diastolic pressure, is when the blood returns to regular blood flow and this is the faintest sound heard and recorded.

Blood Pressure Procedure

1. Measure the bicep to apply appropriate cuff size

2. Wrap cuff firmly around upper arm at heart level; align cuff with brachial artery

3. Palpate brachial artery using fingers (index and middle)

4. Place stethoscope over palpation

5. Manometer should be clearly visible

6. Inflate cuff to ~180-200 mmHg

7. Turn the air-release valve to decrease pressure (2-3 mmHg/sec)

8. Listen to the first and last audible sound

9. Rapidly deflate cuff

10. Give reading – SBP/DBP (i.e. 115/70)

Blood Pressure: Sources of Error

1. Putting on the BP cuff wrong

2. Air-release valve not fully closed

3. Looking at the manometer rather than listening for Korotkoff Sounds

4. Reading a odd value on manual cuff

5. Trying to hear the palpation through the stethoscope 1. This is why we PALPATE

General Circumference Guidelines

1. Measure the waist while facing the subject and measure the hips from the side.

2. All measurements should be made with a flexible yet inelastic tape measure

3. Technician determines the exact anatomical sites of the girth measurements

4. The tape should be placed on the skin surface without compressing the subcutaneous adipose tissue

5. If a Gulick spring—loaded handle is used, the handle should be extended to the same marking with each trial

6. Take duplicate measures at each site, and retest if duplicate measurements are not within 5 mm (0.5 cm)

Waist Circumference Procedure

1. Wrap the tape measure around the subject from the front

2. Place the tape at the narrowest circumference between the umbilicus and the lowest rib

3. Resolve any twists in the tape

4. Cross the tape and switch hands to avoid having your arms cross each other

5. Confirm that the tape is parallel to the ground all the way around the subject

6. Record the measurement in centimeters

7. Take duplicate measures and retest if duplicate measurements are not within 5 mm (0.5 cm)

Hips Circumference Procedure

1. Wrap the tape measure around the subject from the side

2. Place the tape at the largest circumference of the buttocks

3. Resolve any twists in the tape

4. Cross the tap and switch hands to avoid having your arms cross each other

5. Confirm that the tape is parallel to the ground all the way around the subject

6. Record the measurement in centimeters

7. Take duplicate measures and retest if duplicate measurements are not within 5 mm (0.5 cm)

General Skinfold Test Guidelines

• Subjects should wear loose clothing that facilitates skinfold measurement at the appropriate sites

• Avoid making measurements through clothing. If not not possible subtract the thickness of the clothing from your skinfold measurement

• Measurements on right side of body

• Mark sites (use anatomical landmarks)

• Use thumb and index finger to grasp and elevate fold • Caliper should be placed directly on the skin surface, 1 cm away from • A pinch should be maintained while reading the caliper

• Wait 1 to 2 seconds (not longer) before reading caliper

• Caliper perpendicular to fold

• Take duplicate measures at each site, and retest if duplicate measurements are not within 1 to 2 mm

• Rotate through measurement sites, or allow time for skin to regain normal texture and thickness

Triceps Skinfold

1. Have the subject stand facing away from you with the right arm hanging straight down

2. Standing behind the subject, pinch a site 1 cm above the midpoint between the shoulder (acromion process of the scapula) and the tip of the elbow (inferior portion of the olecranon process of the ulna) on the posterior aspect of the triceps

3. Place the jaws of the calipers 1 cm below and perpendicular to the vertical fold

Suprailium Skinfold

1. Grasp the skinfold just above the iliac crest at the level of the anterior axillary line along the natural cleavage of the skinfold (running diagonally down the crest toward the umbilicus)

2. Place the jaws of the calipers 1 cm distal and perpendicular to the diagonal fold

Abdomen Skinfold

1. Grasp a vertical skinfold 2 cm to the subject’s right of and 1 cm above the umbilicus

2. Place the jaws of the calipers 1 cm below and perpendicular to the vertical fold

Chest Skinfold

1. For men, the chest skinfold is the midpoint between the anterior axillary line (the front of the armpit) and the nipple. Grasp the skinfold 1 cm above the midpoint in a diagonal line along the angle of the pectoralis major muscle. Place the jaws of the calipers 1 cm below and perpendicular to the diagonal fold

2. For women, take a diagonal fold as high as possible on the anterior axillary fold (~1/3 between the anterior axillary line and the nipple).

3. Place the jaws of the calipers 1 cm below and perpendicular to the diagonal fold

Thigh Skinfold

1. Have the subject stand with all weight on the left leg and a slight bend at the knee in the right leg

2. Have the subject lift up his or her shorts to gain access to the anterior aspect of the thigh. Technicians often take folds too distally before of longer shorts

3. Take a vertical fold on the anterior aspect of the thigh 1 cm above the halfway point between the inguinal crease and the proximal border of the patella

4. Place the jaws of the calipers q cm below and perpendicular to the vertical fold

Midaxillary Skinfold

1. Take a vertical fold along the midaxillary line at the level of the xiphoid process of the sternum. The subject’s arm is routinely placed on the tester’s shoulder to best gain access to the midaxillary line

2. Place the jaws of the calipers 1 cm below and perpendicular to the vertical fold

Subscapular Skinfold

1. Take a diagonal fold 1 to 2cm from the inferior angle of the scapula. The subject can fold the arm behind the back to expose the scapula (chicken wing); once the spot is located, the arm is returned to the normal position

2. Place the jaws of the calipers 1 cm below and perpendicular to the diagonal fold

Skinfold Sources of Error

• Technician skill • Practice, practice, practice

• Type of SKF caliper • High quality

• Exert constant pressure (Harpenden and Lange)

• Plastic • Do not exert constant pressure

• Client factors • Obesity

• Can exceed the maximum aperture of caliper

• Water retention • Avoid measurement following exercise • Menstrual cycle

Calculation for 7-Site Skinfold

• Body Density

• 7-Site Skinfold Formula (Men)

• 1.112 – 0.00043499 (sf sum) + 0.00000055 (sf sum)2 - 0.00028826 (age)

• 7-Site Skinfold Formula (Female)

• 1.097 – 0.000469971 (sf sum) + 0.00000056 (sf sum)2 - 0.00012828 (age)

• Body Fat Percent

• 7-Site Skinfold Formula

• %bf = [(4.95/ body density) – 4.5] x 100

BIA Procedure (Omron)

1. Measure subject’s height and weight

2. Turn the On/Off button

3. Select GUEST mode then press the set button

4. Select NORMAL by using the Up or Down buttons then press the Set button

5. Input the subject’s height (i.e. 5’7”) by using the Up or Down buttons then press the Set button

6. Input the subject’s weight (i.e. 135 lbs) by using the Up or Down buttons then press the Set button

7. Input the subject’s age by using the Up or Down buttons then press the Set button

8. Select the subject’s sex (male or female) by using the Up or Down buttons then press the Set button

BIA Procedure (Omron)

9. Once all the data is set the READY indicator will display on the screen

10. Have the subject stand with both feet slightly apart

11. Have the subject place both hands on the device by hold the grip electrodes

• Wrap your middle finger around the groove of the handle. Place the palm of the hand on the top and the bottom electrodes. Put the thumbs up, resting on the top of the device.

Correct Incorrect

BIA Procedure (Omron)

12. Have the subject put their arms straight out at a 90° angle to their body

13. Press the START button • Do NOT have the subject hit the START button.

Only the Tester

14. Device will automatically start the measurement

15. After the measurement, BMI will be displayed in the bottom window and percent body fat will be displayed in the top window

BIA Sources of Error

• Analyzer used • Different devices utilized different equations in their software

• Client factors • Must adhere to the pre-test guidelines to minimize error

• Subjects don’t always follow guidelines

• Hydration level • Hypohydration: lower % bf

• Hyperhydration: higher % bf

BIA Sources of Error

• Technician skill • Traditional Whole body BIA requires careful placement of electrodes

and leads to analyzer • More laboratory setting

• Won’t likely use out in the field

• Omron simple, inexpensive, and user friendly • Field base usage

• Temperature • Warm environment: lower % bf

In-Person Lab

• Please wear appropriate clothing for skinfold testing • T-shirt and shorts

• Females: swimsuit top or sports bra

• Make sure to read each procedure thoroughly and have a good understanding

• We will begin testing once the class starts