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Dixie L. Thompson chapter 6 Body Composition
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Dixie L. Thompson chapter 6 Body Composition. Important Terms Fat mass - mass of fat tissues in the body. Fat-free mass - a.k.a. lean body mass. Percent.

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Page 1: Dixie L. Thompson chapter 6 Body Composition. Important Terms Fat mass - mass of fat tissues in the body. Fat-free mass - a.k.a. lean body mass. Percent.

Dixie L. Thompson

chapter

6 Body Composition

Page 2: Dixie L. Thompson chapter 6 Body Composition. Important Terms Fat mass - mass of fat tissues in the body. Fat-free mass - a.k.a. lean body mass. Percent.
Page 3: Dixie L. Thompson chapter 6 Body Composition. Important Terms Fat mass - mass of fat tissues in the body. Fat-free mass - a.k.a. lean body mass. Percent.

Important TermsFat mass - mass of fat tissues in the body.

Fat-free mass - a.k.a. lean body mass.

Percent body fat - % of body composed of fat.

Obesity - abnormal excess of fat tissue.

BMI > 30, Men >25%, Women >38%

Overweight - above recommended wt range.

Body fat distribution or fat patterning

Android-type obesity - Males primarily, closely linked with CHD.

Gynoid-type obesity - mainly seen in females

Page 4: Dixie L. Thompson chapter 6 Body Composition. Important Terms Fat mass - mass of fat tissues in the body. Fat-free mass - a.k.a. lean body mass. Percent.

Essential Fat

• amount of body fat % necessary for good health.

• Allows for temperature regulation, joint cushioning, providing energy.

• 8-12% for women

• 3-5% for men

Page 5: Dixie L. Thompson chapter 6 Body Composition. Important Terms Fat mass - mass of fat tissues in the body. Fat-free mass - a.k.a. lean body mass. Percent.

Common Techniques in Body Composition Assessment

• Skinfold measurements• Hydrostatic weighing• Bioelectrical impedance• Girth measurements• Body mass index

Page 6: Dixie L. Thompson chapter 6 Body Composition. Important Terms Fat mass - mass of fat tissues in the body. Fat-free mass - a.k.a. lean body mass. Percent.
Page 7: Dixie L. Thompson chapter 6 Body Composition. Important Terms Fat mass - mass of fat tissues in the body. Fat-free mass - a.k.a. lean body mass. Percent.

SKINFOLDS

• 3 SITE, 4 SITE, 7 SITE• r=0.70-0.90 with hydrostatic weighing• Rationale: The amount of

subcutaneous fat is proportional to the amount of body fat.

• 1/3 of fat is located subcutaneously• Varies due to age, gender, ethnicity -

must choose the proper Db equation.

Page 8: Dixie L. Thompson chapter 6 Body Composition. Important Terms Fat mass - mass of fat tissues in the body. Fat-free mass - a.k.a. lean body mass. Percent.
Page 9: Dixie L. Thompson chapter 6 Body Composition. Important Terms Fat mass - mass of fat tissues in the body. Fat-free mass - a.k.a. lean body mass. Percent.

Thigh Skinfold (see Figures 5.20 and 5.21)Vertical fold on anterior thigh, midway between

inguinal crease and proximal border of

patella.

Nieman DC. Exercise Testing and Prescription: A Health-Related Approach. 6/e. Copyright ©2007 McGraw-Hill Higher Education. All rights reserved.

Page 10: Dixie L. Thompson chapter 6 Body Composition. Important Terms Fat mass - mass of fat tissues in the body. Fat-free mass - a.k.a. lean body mass. Percent.

Suprailiac Skinfold

Diagonal fold just above iliac crest at

the midaxillary line.

(In the Jackson-Pollock procedure, a diagonal fold is taken with the natural angle

of the iliac crest at the anterior axillary line

immediately superior to the iliac crest).

Nieman DC. Exercise Testing and Prescription: A Health-Related Approach. 6/e. Copyright ©2007 McGraw-Hill Higher Education. All rights reserved.

Page 11: Dixie L. Thompson chapter 6 Body Composition. Important Terms Fat mass - mass of fat tissues in the body. Fat-free mass - a.k.a. lean body mass. Percent.

Nieman DC. Exercise Testing and Prescription: A Health-Related Approach. 6/e. Copyright ©2007 McGraw-Hill Higher Education. All rights reserved.

Chest Skinfold (Fig. 5.18)

Diagonal fold, between anterior axillary fold and nipple, taken one inch from anterior axillary fold.

(In the Jackson-Pollock procedure, the chest/pectoral skinfold site is one half the distance between the anterior axillary line and the

nipple for men, and one third of this distance for women).

Page 12: Dixie L. Thompson chapter 6 Body Composition. Important Terms Fat mass - mass of fat tissues in the body. Fat-free mass - a.k.a. lean body mass. Percent.

Nieman DC. Exercise Testing and Prescription: A Health-Related Approach. 6/e. Copyright ©2007 McGraw-Hill Higher Education. All rights reserved.

Triceps Skinfold (Fig. 5.22)

Vertical fold on posterior aspect of arm, midway between lateral projection of acromion process and inferior margin

of olecranon process.

Page 13: Dixie L. Thompson chapter 6 Body Composition. Important Terms Fat mass - mass of fat tissues in the body. Fat-free mass - a.k.a. lean body mass. Percent.

Nieman DC. Exercise Testing and Prescription: A Health-Related Approach. 6/e. Copyright ©2007 McGraw-Hill Higher Education. All rights reserved.

Abdomen Skinfold Site (Fig. 5.19)

Vertical fold, one inch to the right side of and ½ inch below the navel.

The Jackson-Pollock procedure uses a vertical fold 2 cm to the right of the umbilicus.

Page 14: Dixie L. Thompson chapter 6 Body Composition. Important Terms Fat mass - mass of fat tissues in the body. Fat-free mass - a.k.a. lean body mass. Percent.

Skinfolds

• Accuracy is dependant on tester

• +3.5% accuracy assuming qualified tester

• Accuracy decreases with higher levels of obesity

• Somewhat up close and personal

Page 15: Dixie L. Thompson chapter 6 Body Composition. Important Terms Fat mass - mass of fat tissues in the body. Fat-free mass - a.k.a. lean body mass. Percent.

Accuracy in Measuring Skinfolds

To make the measurements as accurate as possible,– accurately locate the skinfold site,– accurately measure the skinfold, and– choose the appropriate equation for converting

skinfold thickness into %BF.

Page 16: Dixie L. Thompson chapter 6 Body Composition. Important Terms Fat mass - mass of fat tissues in the body. Fat-free mass - a.k.a. lean body mass. Percent.

Hydrostatic Weighing• Often referred to as a criterion method

or gold standard.

• Based on Archimedes’ principle: A person with proportionally more lean mass will weigh more underwater than a person with less lean mass (see figure 6.1)

• Used to calculate total body density

Page 17: Dixie L. Thompson chapter 6 Body Composition. Important Terms Fat mass - mass of fat tissues in the body. Fat-free mass - a.k.a. lean body mass. Percent.
Page 18: Dixie L. Thompson chapter 6 Body Composition. Important Terms Fat mass - mass of fat tissues in the body. Fat-free mass - a.k.a. lean body mass. Percent.

Archimedes Principle

• Bone and Muscle Tissue are denser than water, fat tissue is less dense.

• More FFM or muscle = weighing more in water = higher Db = lower body fat %.

Page 19: Dixie L. Thompson chapter 6 Body Composition. Important Terms Fat mass - mass of fat tissues in the body. Fat-free mass - a.k.a. lean body mass. Percent.

Formula for CalculatingHydrostatic Weight

100 mL = volume of air trapped in gastrointestinal tract that cannot be measured.

Page 20: Dixie L. Thompson chapter 6 Body Composition. Important Terms Fat mass - mass of fat tissues in the body. Fat-free mass - a.k.a. lean body mass. Percent.

Body Density (Db) = body mass (g) / body volume (mL)

Db = Wa / {[(Wa - Ww) / Dw] - (RV + 100 mL)}where; Db = body density (g/mL)

Wa = body mass out of water

Ww = body mass underwater

Dw = density of water (g/mL)

RV = residual lung volume (mL)

100 mL = volume of air trapped in gastrointestinal tract that cannot be measured.

Siri Equation - % body fat = [(4.95 / Db) - 4.50] x 100Brozek Equation - % body fat = [(4.57 / Db) - 4.142] x 100

Page 21: Dixie L. Thompson chapter 6 Body Composition. Important Terms Fat mass - mass of fat tissues in the body. Fat-free mass - a.k.a. lean body mass. Percent.

Two-Compartment Density ModelsNOT ON TEST

• Assume that body is divided into fat mass (FM) and fat-free mass (FFM).

• Assume a constant density of fat and fat-free tissues among individuals.

• Siri (1961) gives a common model: %BF = 495 ÷ Db– 450.

• When components of the FFM differ from the assumed values, estimation of %BF is compromised. Examples: Bone density, hydration. Bone density will vary between races.

• Fortunately, there are two-compartment models for various populations.

• Both hydrostatic weighing and air displacement plethysmography use two-compartment models.

Page 22: Dixie L. Thompson chapter 6 Body Composition. Important Terms Fat mass - mass of fat tissues in the body. Fat-free mass - a.k.a. lean body mass. Percent.

HYDROSTATIC WEIGHING• Accurate but requires costly equipment• Time consuming and very personal• Subjects must follow pre-test guidelines

completely. (no food ingestion 4 hrs prior, smoking, caffeine, exercise).

• 5-10 trials necessary - FATIGUING • light weight clothing needed, removal of air

bubbles from suit, hair, and skin while underwater. • RV can be done before, during or after.• RV errors can cause bf to be off by 3%.

Page 23: Dixie L. Thompson chapter 6 Body Composition. Important Terms Fat mass - mass of fat tissues in the body. Fat-free mass - a.k.a. lean body mass. Percent.

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Page 24: Dixie L. Thompson chapter 6 Body Composition. Important Terms Fat mass - mass of fat tissues in the body. Fat-free mass - a.k.a. lean body mass. Percent.

Air-displacement plethysmography (BodPod)

$37,999 , mobile, 5 minutes• Relatively new - 1989• Must wear tight fitting swimsuit and cap• Claustrophobia a concern with some• Fitness Center and Pediatric versions

Page 25: Dixie L. Thompson chapter 6 Body Composition. Important Terms Fat mass - mass of fat tissues in the body. Fat-free mass - a.k.a. lean body mass. Percent.

Air-Displacement• Subject sits in a calibrated "pod" and air is

displaced instead of water.

• Similar results to hydrostatic weighing

• Appears to be an accurate alternative - standard error of 2.2 - 3.7% body fat.

• "Increased research and technology should yield more accurate results in the future." In other words RV is a concern.

Page 26: Dixie L. Thompson chapter 6 Body Composition. Important Terms Fat mass - mass of fat tissues in the body. Fat-free mass - a.k.a. lean body mass. Percent.

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Page 27: Dixie L. Thompson chapter 6 Body Composition. Important Terms Fat mass - mass of fat tissues in the body. Fat-free mass - a.k.a. lean body mass. Percent.
Page 28: Dixie L. Thompson chapter 6 Body Composition. Important Terms Fat mass - mass of fat tissues in the body. Fat-free mass - a.k.a. lean body mass. Percent.
Page 29: Dixie L. Thompson chapter 6 Body Composition. Important Terms Fat mass - mass of fat tissues in the body. Fat-free mass - a.k.a. lean body mass. Percent.

Bioelectrical ImpedanceAnalysis (BIA)

• Electrical current travels more easily through tissue containing water and electrolytes.

• Fat does not contain much water; therefore, electrical flow is impeded.

• Fat can be estimated by the impedance encountered when electrical currents pass through the body.

(continued)

Page 30: Dixie L. Thompson chapter 6 Body Composition. Important Terms Fat mass - mass of fat tissues in the body. Fat-free mass - a.k.a. lean body mass. Percent.

Bioelectrical ImpedanceAnalysis (BIA) (continued)

• There are a number of commercially available BIA devices.

• Values are typically within 4% of those obtained with hydrostatic weighing.

• It is important to choose the proper equation for estimating %BF. The relationship between % BF and impedance varies among populations.

• It is critical that the person being tested is normally hydrated.

Page 31: Dixie L. Thompson chapter 6 Body Composition. Important Terms Fat mass - mass of fat tissues in the body. Fat-free mass - a.k.a. lean body mass. Percent.

BIA Problems

• Electrolyte status may be altered due to: • alcohol consumption (48 hrs)• food consumption (4 hrs)• recent exercise (12 hrs)• diuretic therapy (Physician approved)• menstrual cycle (avoid 3 days prior through

three days following)• Oil and lotions should be removed from the

skin

Page 32: Dixie L. Thompson chapter 6 Body Composition. Important Terms Fat mass - mass of fat tissues in the body. Fat-free mass - a.k.a. lean body mass. Percent.

Common Girth Measurements• Waist: most narrow part of the torso

between the xiphoid process and the umbilicus

• Abdomen: circumference of the torso at the level of the umbilicus

• Hips: maximal circumference of the buttocks above the gluteal fold

• Thigh: largest circumference of the right thigh below the gluteal fold

Page 33: Dixie L. Thompson chapter 6 Body Composition. Important Terms Fat mass - mass of fat tissues in the body. Fat-free mass - a.k.a. lean body mass. Percent.

Abdominal Obesity• A waist-to-hip ratio of ≥0.95 for

men or ≥0.86 for women is considered too high according to ACSM standards.

• A waist circumference greater than 102 cm in men or 88 cm in women significantly increases the risk of obesity-related disease.

Page 34: Dixie L. Thompson chapter 6 Body Composition. Important Terms Fat mass - mass of fat tissues in the body. Fat-free mass - a.k.a. lean body mass. Percent.

Body Mass Index (BMI)

• Criterion used to classify adequacy of weight for height

• Does not indicate level of body fatness• Weight (in kilograms) divided by

squared height (in meters)<18.5 kg · m–2 = underweight

18.5 to 24.9 kg · m–2 = normal weight25 to 29.9 kg · m–2 = overweight

≥30 kg · m–2 = obese

Page 35: Dixie L. Thompson chapter 6 Body Composition. Important Terms Fat mass - mass of fat tissues in the body. Fat-free mass - a.k.a. lean body mass. Percent.

Body Mass Index (BMI)

The ratio of mass to height2

BMI = body mass (kg) / body height (m)2

for example

BMI = 80 (kg) / 1.72 (m) = 27.68 kg/m2

Page 36: Dixie L. Thompson chapter 6 Body Composition. Important Terms Fat mass - mass of fat tissues in the body. Fat-free mass - a.k.a. lean body mass. Percent.

Why Use BMI?• High BMI associated with a higher

mortality rate due to CVD, Cancer, Diabetes, and other diseases.

• Easy - Private

• No Training Involved

• Better than HT/WT tables

Page 37: Dixie L. Thompson chapter 6 Body Composition. Important Terms Fat mass - mass of fat tissues in the body. Fat-free mass - a.k.a. lean body mass. Percent.

Why Not To Use BMI• Does not reflect actual body fat content

• Does not consider muscle weight

• +5 error rate

Page 38: Dixie L. Thompson chapter 6 Body Composition. Important Terms Fat mass - mass of fat tissues in the body. Fat-free mass - a.k.a. lean body mass. Percent.
Page 39: Dixie L. Thompson chapter 6 Body Composition. Important Terms Fat mass - mass of fat tissues in the body. Fat-free mass - a.k.a. lean body mass. Percent.

Calculating Target Body Weight

• It is often important to help clients determine a healthy and reasonable weight.

• Calculating target body weight requires knowledge of current body weight, %BF, and desired %BF.

Page 40: Dixie L. Thompson chapter 6 Body Composition. Important Terms Fat mass - mass of fat tissues in the body. Fat-free mass - a.k.a. lean body mass. Percent.

Formula for CalculatingTarget Body Weight

Page 41: Dixie L. Thompson chapter 6 Body Composition. Important Terms Fat mass - mass of fat tissues in the body. Fat-free mass - a.k.a. lean body mass. Percent.

Comparison of Two Individuals With Same Total Mass But

Different LBM

Adapted from M.L. Pollock and J.H. Wilmore, 1990, Exercise in health and disease, 2nd ed. (Philadelphia: Saunders).