Concordance Among Bioelectrical Impedance Analysis Measures of Percent Body Fat in Athletic Young Adults.

The purpose of this investigation was to determine the agreement among three bioelectrical impedance analysis devices (BIA) in athletic young adults. Fifty-one participants (26 men and 25 women) were assessed for percent body fat (PBF) using an arm-to-arm bipolar single-frequency device (ABIA), a leg-to-leg single-frequency device (LBIA), and an octopolar multi-frequency BIA device (MFBIA). PBF was measured with the three devices in a randomized, counterbalanced order. Repeated measures ANOVA revealed significant ( p < 0.001) differences in PBF estimates among all devices (ABIA = 19.1 ± 7.2%, LBIA = 21.6 ±7.5%, and MFBIA = 22.9 ± 8.8%). Pearson's Correlations revealed a strong relationship between ABIA and MFBIA in both men ( r = 0.948) and women ( r = 0.947) and a moderately-strong relationship between LBIA and MFBIA ( r = 0.870 and 0.679, respectively). Lin's concordance coefficient revealed moderately-strong concordance between ABIA and MFBIA in men ( ρ c = 0.800) and women ( ρ c = 0.681) and between LBIA and MFBIA ( ρ c = 0.846 and ρ c = 0.651, respectively). These data indicate a strong agreement among all three devices, suggesting that any of them could be used to track changes in PBF over time. However, the significant differences in PBF values among devices imply that best practice for monitoring body composition should be to use one device consistently over time for a reliable assessment.