Relationship Of Fat-free Mass And Fat Mass To Body Weight In College Female Athletes

Abstract

Body mass differs widely across the sports spectrum in female athletes. While some sports are dominated by large athletes, other sports participants benefit from a smaller size and/or are limited by weight class. The most traditional measure of body composition has been %fat with less frequent emphasis on the major components of body composition: fat-free mass (FFM) and fat mass (FM). FFM is the functional component since as it is closely associated with maximal voluntary strength, while FM plays an important role in energy balance. With the ever increasing emphasis on control and manipulation of these components in modern sports, closer observation should be given to the relationship between FFM and FM accumulation. PURPOSE: To determine the relationship of FFM and FM to height and body mass across a wide-range of size typically observed in college female athletes. METHODS: One hundred and thirty-two NCAA Division-II female athletes (age = 19.9 ± 1.2 y, height =169.1 ± 7.9 cm, body mass = 67.8 ± 12.2 kg) volunteered to participate. Body composition was assessed using dual-energy x-ray absorptiometry (DEXA) to assess regional estimates of lean (bone, muscle, etc.) and fat tissue which allowed determination FFM and FM. RESULTS: Height was linearly correlated with body mass (r=0.58). FFM and FM were significantly related to height (r = 0.63 and 0.40, respectively) and body mass (r = 0.91 and 0.93, respectfully), with the relationships being linear in all four cases. FFM accumulated at approximately 0.35 kg/cm height and 0.50 kg/kg body mass; accounting for 91% of the variance in body mass, while FM accounted for only 9%. The greatest accumulation of FFM was at a height of 169 cm (0.402 kg/cm height) and body mass of 105 kg (0.663 kg/kg). The relationship between FFM and FM was significant (r = 0.71) and curvilinear. Accumulation of FM per kg of FFM increased at FFM > 55 kg. CONCLUSIONS: In female athletes, body mass appears to be the significant determinant of FFM accumulation. The accumulation of FM is determined by FFM, while the rate of accumulation of FM increases significantly at a threshold of 55 kg FFM.