A comparison of leg-to-leg bioelectrical impedance and underwater weighing methods in measuring body composition in Caucasian and African American football athletes

The purpose of this study was to validate leg-to-leg bioelectrical impedance analysis (BIA) methodology for estimating body composition in ethnically mixed football athletes. Sixty-four Caucasian and 36 African American Division IAA football athletes took part in this study. Their mean age ± SD was 20.2 ± 1.9 yr and their body mass index was 29.2 ± 4.8 kg/m². Age, body mass index, and percent body fat did not differ significantly between ethnic groups. Fat free mass (FFM) and percent body fat was also estimated from underwater weighing (UW), seven-site skinfold measurement (SK), and BIA. A significant correlation in estimating FFM was found between underwater weighing and BIA (r = 0.94, p ≤ 0.001; SEE 3.7 kg), and between underwater weighing and skinfold thickness measurement (r = 0.97, p ≤ 0.001; SEE 2.6 kg). The mean difference in estimation of FFM between underwater weighing and BIA was -0.46 ± 3.8 kg. No significant correlation (r = 0.10, p = .166) was found between the estimation of FFM from underwater weighing and the difference in estimation of FFM between underwater weighing and BIA. This indicated there was no systematic underestimation or overestimation of FFM in either Caucasian or African American athletes. In conclusion, the leg-to-leg BIA system provided a quick and accurate method of determining body composition in football athletes compared to conventional underwater weighing.