Combining Anthropometry and Bioelectrical Impedance Analysis to Predict Body Fat in Female Athletes

Context Accurate methods for predicting the percentage of body fat (%Fat) in female athletes are needed for those who lose weight before competition. Methods mandated by sport governing bodies for minimal weight determination in such athletes lack validation. Objective To (1) determine whether combining anthropometry using skinfold (SF) thicknesses and bioelectrical impedance analysis (BIA) in a 3-compartment (3C) model would improve the prediction of %Fat in female athletes and (2) evaluate the Slaughter SF equation. Design Cross-sectional study. Setting Laboratory-based study during the preseason for collegiate sports. Participants A total of 18 National Collegiate Athletic Association Division I female athletes were recruited from swim and gymnastics teams. Main Outcome Measure(s) We measured %Fat based on a 4-compartment (4C) criterion incorporating body density (air-displacement plethysmography), total body water (D2O dilution), and bone mineral mass (dual-energy x-ray absorptiometry) compared with predicted %Fat using SF alone (Slaughter equation), BIA (single frequency for total body water estimate), and combined SF and BIA (3C model). Results For the %Fat determined using the 4C criterion, the highest adjusted coefficient of determination and lowest prediction error (r2; ±standard error of estimate) were for the 3C model (r2 = 0.87; ±2.8%), followed by BIA (r2 = 0.80; ±3.5%) and SF (r2 = 0.76; ±3.8%; P values < .05 for all). Means differed for the %Fat determined using BIA (26.6% ± 7.5%) and the 3C (25.5% ± 7.2%) versus 4C model (23.5% ± 7.4%; analysis of variance and post hoc analyses: P values < .05). The SF estimate (24.0% ± 7.8%) did not differ from the 4C value. Conclusions Combining SF and BIA might improve the prediction and lower the prediction error for determining the %Fat in female athletes compared with using SF or BIA separately. Regardless, the Slaughter equation for SF appeared to be accurate for determining the mean %Fat in these female athletes.