Use of bioelectrical impedance analysis measurements as an evaluation for participating in sports

Bioelectrical impedance analysis (BIA) has potential in the area of sports and exercise as a method for evaluating body composition in groups of athletes. BIA probably holds less promise for detecting small changes in percentage fat within an individual. Available data in athletes have indicated an urgent need to control for testing conditions such as hydration, temperature, glycogen stores, and preceding diet and exercise. There are almost no data available for female athletes, but acceptable results have been reported in males when conditions are well controlled. There is, however, a tendency for BIA to overestimate percentage body fat, and more so in African American athletes. BIA is also potentially useful for assessing the hydration status in wrestlers, but it is advisable to use untransformed BIA measurements rather than to convert resistance measurements to body fat because of the questionable hydration status in these athletes. Untransformed results are potentially useful in evaluating the clinical status of athletes at risk for abnormal hydration because of extreme dieting practices.