Psycology - Lab

Body Composition Assessment

Purpose:

The purposes of this laboratory experience is to develop your skill in using the skinfold and bioelectrical impedance analysis (BIA) to assess body composition and to use common anthropometric measures such as body mass index (BMI) and waist-to-hip ratio (WHR) to estimate health risks associated with being overweight. You will also gain knowledge of hydrodensitometry (hydrostatic weighing), the air displacement technique, and duel energy x-ray absorptiometry (DEXA) methods to assess body composition.

Background:

Relative body fat percentage is a good indicator of general health and fitness. High percent body fat is associated with increased risks for several diseases including diabetes, hypertension (high blood pressure), certain cancers, cardiovascular disease, and hyperlipidemia (high cholesterol) among others. Conversely, appropriate body fat is associated with increased longevity and reduced risk for developing the conditions mentioned above. Body composition is estimated in order to determine a healthy body weight, to monitor growth in children, to monitor health status in malnourished or diseased populations, and to estimate competitive body weight for athletes.

Methods: (skinfolds, BIA, anthropometric)

Equipment:

General:

· Anthropometric measuring tapes

· Marking pens

· Body weight scale

· Stadiometer

Skinfold Measurement:

∙ Plastic or metal skinfold calipers, preferably metal calipers

Bioelectrical Impedance Analysis:

∙ BIA analyzer (OMRON)

Testing Procedures:

Work in groups of 2 - 3 for all measurements. Your write-up will include data for 2 subjects. One student will be measured, one will be measuring, and one will record. Rotate positions until all students have performed all roles.

General:

∙ Obtain demographic information from client and fill-in Data collection form

Skinfolds:

∙ Follow the measuring procedures for skinfold measurement.

∙ Use the standardized anatomical descriptions for skinfold sites to locate each site. Mark the six skinfold sites with the surgical marking pen.

BIA (OMRON):

∙ Enter data into OMRON.

∙ Have client grasp handles firmly and hold out in front of themselves with arms parallel to the ground and legs shoulder width apart.

∙ Hit START button.

Anthropometric Measures:

∙ BMI = wt/ht2

O Wt = weight in kilograms

O Ht = height in meters

∙ Waist-to-Hip ratio = C-waist/C-hip

O C-waist = circumference of waist at narrowest point between xiphoid process and umbilicus

O C-hip = circumference of hip at widest point between iliac crest and gluteal fold

Data Analysis:

Skinfolds:

∙ Calculate body densities for at least 3 subjects (may include yourself as one) using all 3 equations [converting skinfold thickness to body density (Db)]

∙ Convert to percent body fat using the population specific equations

∙ Classify the percent body fat for your subjects using the most appropriate equation

BIA:

∙ Measure percent body fat 2 times for each client

∙ Record average of the 2 measurements

∙ Classify the average value of these measures

Anthropometric Measures:

∙ Calculate your client’s BMI

O Classify your client’s BMI

∙ Calculate your client’s WHR

O Classify your client’s WHR

Skinfold Measuring Procedures

1. Locate the sites

a. All sites are measured on right side of body

2. Mark the site with a long line along the crest of the intended fold, and a short hash mark perpendicular to that line at the intended measuring spot.

3. Measure the skinfold thickness by:

a. Locate ‘pinch’ site with left hand approximately 1cm above measurement site along the long line.

b. With thumb and forefinger of left hand approximately 5-7cm apart pinch the site perpendicular to the long line.

c. By drawing the thumb and forefinger together the separation of subcutaneous fat from muscle should occur. Be firm!

i. Having client gently and briefly flex muscle below site will help ensure that no muscle is being measured.

ii. The long line should be at the crest of the skinfold.

d. Place caliper over the skinfold above the short line.

e. Release calipers on short line midway between base of body and crest of skinfold.

i. Do NOT let go of skinfold in left hand!

ii. Take reading after 2 seconds to nearest 0.1mm.

f. Release calipers (open jaws first!) and remove from skinfold.

g. Record measurement.

4. Repeat procedure for other sites.

a. Measurements are to be taken in rotational order.

i. Do not measure same site consecutively.

5. Continue measurements at least 2 times per site.

a. Continue taking measurements until two values are within 10% of each other.

b. Report the mean of the 2 closest values for each site.

Skinfold Site Locations

1. Abdominal - Vertical fold – umbilicus – 3cm lateral / 1cm inferior to umbilicus

2. Chest (males only) - Diagonal fold – axilla and nipple – one-half distance between axilla and nipple

3. Subscapular - Diagonal fold – vertebral border and inferior angle of scapula – diagonal line coming from vertebral border, 1-2cm below inferior angle

4. Suprailiac - Diagonal fold – iliac crest – diagonal above iliac crest along the anterior axillary line

5. Thigh - Vertical fold – inguinal crease and patella – anterior aspect of thigh, midway between inguinal fold and proximal border of patella.

6. Triceps - Vertical fold – acromial process and olecranon process – midway between acromial process and olecranon process on posterior aspect of arm

7. Midaxillary - Vertical fold; on the midaxillary line at the level of the xiphoid process of the sternum. (An alternate method is a horizontal fold taken at the level of the xiphoid/sternal border in the midaxillary line.)

Data Collection Form (subject 1)

Name___________________ Age_________________ Weight_________________

Height___________________ Gender_________________ Ethnicity_________________

____________________________________________________________________________________

Db General %BF Pop. Spec. %BF

EQ 1_________________ 1_______________ 1___________________

EQ 2_________________ 2_______________ 2___________________

EQ 3_________________ 3_______________ 3___________________

_____________________________________________________________________________________

BIA - % Body Fat

Trial 1 Trial 2 Average

Classification___________________

_____________________________________________________________________________________

Anthropometric

Height__________(m) Weight____________(kg) BMI_____________ Classification____________

Waist___________(cm) Hip____________(cm) WHR_____________ Classification____________

Data Collection Form (subject 2)

Name___________________ Age_________________ Weight_________________

Height___________________ Gender_________________ Ethnicity_________________

____________________________________________________________________________________

Db General %BF Pop. Spec. %BF

EQ 1_________________ 1_______________ 1___________________

EQ 2_________________ 2_______________ 2___________________

EQ 3_________________ 3_______________ 3___________________

_____________________________________________________________________________________

BIA - % Body Fat

Trial 1 Trial 2 Average

Classification___________________

_____________________________________________________________________________________

Anthropometric

Height__________(m) Weight____________(kg) BMI_____________ Classification____________

Waist___________(cm) Hip____________(cm) WHR_____________ Classification____________

Data Collection Form (subject 3)

Name___________________ Age_________________ Weight_________________

Height___________________ Gender_________________ Ethnicity_________________

____________________________________________________________________________________

Db General %BF Pop. Spec. %BF

EQ 1_________________ 1_______________ 1___________________

EQ 2_________________ 2_______________ 2___________________

EQ 3_________________ 3_______________ 3___________________

_____________________________________________________________________________________

BIA - % Body Fat

Trial 1 Trial 2 Average

Classification___________________

_____________________________________________________________________________________

Anthropometric

Height__________(m) Weight____________(kg) BMI_____________ Classification____________

Waist___________(cm) Hip____________(cm) WHR_____________ Classification____________

Estimation of Body Fat Percent Using Skinfold Measurements

1. Use all the all the equations below to calculate body density (Db), and then calculate percent body fat by using the general conversion and the population specific equation (table on next page).

2. Carry out as many decimal places as possible for these equations.

Db to BODY FAT CONVERSION EQUATIONS

Male - %fat = (4.95/Db) - 4.50

Female - % fat = (5.01/Db) – 4.57

Results:

Create a table that includes a summary of your main findings. Percent body fat for each technique, WHR, BMI, body weight and the classification of them (except body weight).

Class Discussion Questions:

1. What are 3 potential sources of measurement error using the skinfold method?

2. What are 2 potential sources of measurement error using the BIA method?

3. What are 2 potential sources of error in measuring body composition using the hydrostatic weighing method?

4. What client populations may have difficulty performing the hydrostatic weighing procedures?

Discussion Questions:

Remember to refer to the lab lecture notes for an additional resource to these questions.

1. Which value (give the specific %BF) would you report to your clients and from which technique did you get this value? Why, specifically, did you choose this technique as the one to report?

2. Based on the WHR, is your client apple or pear-shaped? Is your client at risk for diseases associated with upper-body obesity? Explain.