Body Composition and Performance

Athletic performance is, to a large degree, dependent on the athlete's ability to sustain power (both anaerobically and aerobically) and to overcome resistance, or drag. Both of these factors are interrelated with the athlete's body composition. Coupled with the common perception of many athletes who compete in sports where appearance is a concern for both the athlete and the common perception of these athletes ( swimming, diving, gymnastics, figure skating), attainment of an"ideal"body composition often becomes a central theme of training. Besides the aesthetic and performance reasons for wanting to achieve an optimal body composition, there may also be safety reasons.

In the minds of athletes, there is an inherent conflict between overcoming the resistance, or drag, associated with sport and having enough energy to sustain power output over the entire course of a competition or training session. Athletes view weight reduction (i.e., being smaller) as an effective means of overcoming resistance (imagine the position and profile of a cyclist or speedskater to reduce drag), and the common way to achieve weight reduction is to reduce caloric intake. However, having the capacity to sustain power output requires eating to at least a state of energy balance. It appears that many athletes believe this latter point (i.e., sustaining power output) is not as important as reducing drag, so the athletes consume inadequate calories.

An athlete who is carrying excess weight may be more prone to injury when performing difficult skills than the athlete with a more optimal body composition. However, when athletes attempt to achieve an optimal body composition, their methods are often counterproductive. Diets and excessive training often result in such a severe energy deficit that, although total weight may be reduced, the constituents of weight also change, commonly with a lower muscle mass and a relatively higher fat mass. The resulting higher body fat percentage and lower muscle mass inevitably result in a performance reduction that motivates the athlete to follow regimens that produce even greater energy deficits. This downward energy intake spiral may be the precursor of eating disorders that place the athlete at serious health risk. Therefore, although achieving an optimal body composition is useful for high-level athletic performance, the processes athletes often use to attain an optimal body composition may reduce athletic performance, place athletes at a higher injury risk, increase health risks, and predispose them to eating disorders.

At times, wrongly, achieving ideal body composition becomes the focus of training instead of sustaining power and overcoming drag, a line that blurs in sports like swimming, diving, gymnastics, and figure skating.

Many people have the unhealthy mind-set that food, regardless of the amount and type, is"fat producing."A much healthier (and from the point of view of an athlete, more appropriate) mind-set is that food is the provider of the fuel and nutrients associated with muscle energy.

Body fat percentage should be thought of as having an approximate range for different sports, and it's OK for athletes to fall anywhere on that sport-specific range. Within some reasonable bounds, having a relatively low body fat percentage may aid athletic performance by improving the strength-to-weight ratio: For a given weight, more of it is represented by lean mass that is power producing and less of it by fat mass that represents stored fuel. It also helps by lowering the resistance, or drag, an athlete has as he or she moves through the air, swims in water, or skates on ice; the smaller the body profile, the less resistance the body is likely to produce.

Less resistance is so important for some sports (typically the faster you go, the greater the importance of drag reduction) that performance techniques are based on reducing drag. After their initial strides off the starting line, for instance, speed-skaters spend the entire race bent over to reduce wind resistance. Cyclists wear special streamlined helmets and clothing, position their bodies on the bicycle to reduce drag, and even strategize about the best time to sprint ahead of the cyclist in front of them. Going too soon can lead to premature exhaustion because it takes a great deal more energy (12 to 17 percent more) for the cyclist in the lead facing the air resistance to go the same speed. A gymnast who weighs 110 pounds (50 kilograms) and is 5 feet (152 centimeters) tall with a body fat percentage of 15 percent will have a lower air resistance (i.e., less drag) tumbling through the air than a gymnast with the same weight and height but with a body fat percentage of 20 percent. Figure skaters are increasingly required to perform jumps with more in-air revolutions to stay competitive. The greater the number of revolutions, the more difficult it is for a larger figure skater to complete the jump. For some sports, however, this may make little or no difference. It's hard to imagine how a lineman on a football team is concerned about air resistance. Nevertheless, even for this athlete, having a high strength-toweight ratio makes a difference because the lineman who can move his mass more quickly and powerfully will knock over the lineman who moves more slowly. Even a powerlifter gains an advantage if, in meeting a weight category, more of the lifter's weight is composed of muscle and less is composed of fat. In sports where being aerodynamic helps, body composition makes a difference because, pound for pound, fat takes up more space than lean tissue does because it is less dense.

Pathologic Weight Control in Athletes: Eating Disorders