1. Body Composition

2. Body Build, Size, and Composition
Body build is the form or structure of the body.
• Muscularity
• Linearity
• Fatness
Body size is determined by height and weight.
Body composition refers to the chemical composition
of the body
• Fat mass
• Fat-free mass

3. Three Models of Body Composition
Adapted, by permission, from J.H. Wilmore, 1992, Body weight and body composition. In Fasting, body
weight, and performance in athletes: Disorders of modern society, edited by R. Brownell and J.H. Wilmore
(Baltimore, MD: Lippincott, Williams, and Wilkins), 77-93.

4. Did You Know . . . ?
Fat-free mass is composed of all of the body’s nonfat
tissue, including bone, muscle, organs, and
connective tissue. Lean body mass includes all fat-
free mass along with essential fat. Lean body mass
is difficult to measure, so the fat mass/fat-free mass
model is most often used.

5. Did You Know . . . ?
Body composition is a better indicator of fitness than
body size and weight. Being overfat (not necessarily
overweight) has a negative impact on athletic
performance. Standard height–weight tables do not
provide accurate estimates of what an athlete should
weigh because they do not take into account the
composition of the weight. An athlete can be
overweight according to those tables yet have very
little body fat.

6. Assessing Body Composition
• Densitometry (hydrostatic weighing)
• Skinfold fat thickness
• Bioelectric impedance

7. Densitometry
• Body density = Body mass ÷ Body volume
• Body mass = measured on a regular scale
• Body volume = measured using hydrostatic
(underwater) weighing accounting for
water density and air trapped in the
lungs
• % body fat = (495 ÷ body density) – 450

8. Underwater Weighing Technique to
Determine Density of the Body
Tom Pantages

9. Dual-Energy X-Ray Absorptiometry
Machine
Photo courtesy of Hologic, Inc.

10. Bod Pod device
Photo courtesy of Life Measurement, Inc.

11. Measuring Skinfold Fat Thickness at
the Triceps Skinfold Site
© Human Kinetics

12. Bioelectric Impedance Technique for
Assessing Relative Body Fat
© Human Kinetics

13. Did You Know . . . ?
Inaccuracies in densitometry are due to the variation
in the density of the fat-free mass from one individual
to another. Age, sex, and race affect the density of fat-
free mass.

14. Body Composition and
Performance
Maximizing Fat-Free Mass
• Desirable for strength, power, and muscular
endurance
• Undesirable for endurance or jumping sports if the
result is weight gain
Minimizing Relative Body Fat
• Desirable, especially in sports in which the body
weight is moved through space
• Improves speed, endurance, balance, agility, and
jumping ability

15. Relative Body Fat in Elite Female
Track and Field Athletes
Data from J.H. Wilmore et al., 1977, “Body physique and composition of the female distance runner,” Annals of the New York
Academy of Sciences 301: 764-776.

16. Risks With Severe Weight Loss
• Dehydration
• Chronic fatigue
• Disordered eating and eating disorders
• Menstrual dysfunction
• Bone mineral disorders

17. Appropriate Weight Guidelines
• Maximize performance within the specific sport
• Are based on body composition
• Emphasize relative body fat rather than total body mass
• Use a range of relative fat values that are considered
acceptable for the athlete’s age and sex

18. Achieving Optimal Weight
• Combine proper diet with exercise.
• Lose no more than 1.0 kg (2 lb) per week.
• Reduce caloric intake to 200 to 500 kcal less than daily
energy expenditure.
• Use moderate resistance and endurance training.