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.