Body composition –chapter 14
Knowing a person’s body composition is more valuable for predicting performance potential
then merely knowing height and weight.
Densitometry is one of the best methods for assessing body composition and has long been
considered the most accurate, although it does carry certain risks of error. It involves calculating
the density of the athlete’s body by dividing body mass by body volume, which is typically
determined via hydrostatic weighing or air displacement. Body composition can be calculated,
although there is some margin of error.
Dual-energy x-ray absorptiometry, originally developed for estimating done density and bon e
mineral content, is now capable of providing accurate estimates of total body composition fat
mass and fat-free mass.
Field techniques for assessing body composition include measuring skinfold fat thickness and
bioelectric impedance. These techniques are less costly and more accessible to the athlete and
the coach than are laboratory techniques.
The ideal body composition varies with different sports, but in general, the less fat mass, the
greater the performance.
Maximizing fat-free mass is desirable for athletes in sports that require strength, power, and
muscular endurance but could be a hindrance to endurance athletes, who must be able to move
their total body mass for extended periods, and jumpers, who must move their body mass
vertically or horizontally for distance.
The degree of fatness has more influence on performance then does total body weight. In
general, the greater the relative body fat, the poorer the performance. Possible exceptions
include heavyweight weightlifters, sumo wrestlers, and swimmers.
Many sports enforce weight standards with the goal of ensuring that the athletes are of optimal
body size for participation. Unfortunately, athletes often turn to questionable, ineffective, or
even dangerous methods of weight loss to reach their weight goal.
Severe weight loss in athletes can cause potential health problems, such as dehydration, chronic
fatigue, disordered eating, menstrual dysfunction, and bone mineral disorders.
The chronic fatigue symptoms that ofteb accompany severe wight loss mimic those of
overtraining. This fatigue also can be caused by substarte depletion.
Body weight standards should be based on body compostion. Thus, these standards should
emphasize relative body fat rather than total body mass.
For each sport, a range of values should be established, recognizing the importance of individual
variation, methodological error, and sex diffe3rences.
When severe (very low calorie) diets followed, much of the weight loss occurs is from water, not
Most severe diets limit carbohydrate intake, depleting carbohydrate stores. Water i