Validity of leg-to-leg bioelectrical impedance measurement in males

Background. This study determined the validity of the leg-to-leg bioelectri cal impedance analysis (BIA) system (Tanita Body Fat Analyzer, TBF 105, Tan ita Corporation of America, Inc., Arlington Heights, IL) in estimating body composition in males. Methods. Experimental design: fat-free mass (FFM) was estimated using BIA a nd underwater weighing, and compared. Setting: subjects were recruited from the community. Participants: heterogeneous group of males (N=192) was recr uited, with a mean +/- SD age of 39.0 +/- 116.8 yrs; body mass index, 26.0 +/-4.0 kg/m(2), percent body fat, 18.1 +/-8.9%. Measures: prior to BIA test ing, subjects were required to adhere to standard BIA testing guidelines, a nd bioelectrical impedance was measured in subjects standing erect with bar e feet on the analyzer's footpads, and wearing a swimsuit. Underwater weigh ing was conducted using standard procedures, with direct measurement of res idual volume. Results. A Bland-Altman plot of difference between FFM measured by underwat er weighing and BIA versus average FFM by the two methods showed no systema tic difference (mean difference, 0.07 +/-3.5 kg). FFM was estimated at 66.3 +/-8.6 kg with underwater weighing, and 66.2 +/-7.7 kg with BIA (r=0.92, p <0.001; SEE 3.5 kg). Conclusions. These data indicate that the leg-to-leg bioelectrical impedanc e system accurately assesses FFM in a heterogenous group of males when comp ared to underwater weighing.