Purpose: To evaluate the accuracy of leg-to-leg bioelectrical impedance analysis (BIA) in assessing fat-free mass (FFM) using the TBF-300WA in comparison with hydrostatic weighing (HW) and skinfolds (SK) in high-school (HS) wrestlers in a hydrated state.
Methods: Body composition was determined by BIA, HW, and three-site SK in 129 HS wrestlers (mean +/- SD, age: 15.5 +/- 1.3, height 1.70 +/- 0.08 m, body mass 65.6 +/- 13.1 kg). For all methods, body density (Db) was converted to percent body fat (%BF) using the Brozek equation. Hydration state was quantified by evaluating urine specific gravity.
Results: There were no significant differences for estimated FFM between BIA (56.9 +/- 8.4 kg) and HW (56.2 +/- 9.9 kg) or between SK (56.1 +/- 8.9 kg) and HW. The standard errors of estimate for FFM with HW as the reference method were 3.64 kg for BIA and 1.97 kg for SK. Significant correlations were found for FFM between HW and BIA (r = 0.93, P < 0.001), and between HW and SK (r = 0.98, P < 0.001). The FFM difference between BIA and HW was significantly correlated with the FFM average of the two methods (r = -0.39, P < 0.001). The FFM difference between SK and HW was also significantly correlated with the FFM average (r = -0.44, P < 0.001).
Conclusions: This study demonstrates that SK should be considered as the preferred field method of estimating the FFM of HS wrestlers because of its greater individual precision than the leg-to-leg BIA method. Although the BIA is an attractive assessment tool and easy to use, it should be recommended as an alternative to the SK method only when trained skinfold technicians are not available.