Purpose: To evaluate the accuracy of multifrequency bioelectrical impedance analysis (MFBIA) in assessing fat-free mass (FFM) in comparison with hydrostatic weighing (HW) and skinfolds (SK) in high school wrestlers in a hydrated state. Methods: Body composition was determined by MFBIA, HW, and three-site SK in 72 high school wrestlers (mean ± SD; age = 15.3 ± 1.4 yr, height = 1.71 ± 0.08 m, body mass = 67.3 ± 13.4 kg). Hydration state was quantified by evaluating urine specific gravity. Results: There were no significant differences for estimated FFM between MFBIA (57.2 ± 9.5 kg) and HW (57.0 ±10.1 kg) or SK (56.4 ± 8.8 kg). The SEE for FFM with HW as the reference method were 2.73 kg for MFBIA and 2.66 kg for SK. Correlations were found for FFM between HW and MFBIA (r = 0.96, P < 0.001) and between HW and SK (r = 0.97, P < 0.001). A systematic bias was found for MFBIA because the difference between MFBIA and HW correlated with the FFM average of the two methods (r = -0.22, P < 0.001). A bias was also seen between SK and HW and correlated with the FFM average (r = -0.47, P < 0.001). Conclusions: This study demonstrates that MFBIA provides similar estimates of FFM when compared with HW in a heterogeneous high school wrestling population during a hydrated state. MFBIA is an attractive assessment tool, easy to use, and may be considered as an alternative field-based method of estimating the FFM of high school wrestlers.
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