Estimation of whole-body skeletal muscle mass by bioelectrical impedance analysis in the standing position

Abstract

Summary Objective To develop a clinical method for evaluating skeletal muscle (SM) mass using whole-body bioelectrical impedance (BI) analysis in the standing position. Subjects Two hundred and forty-four volunteers (men=106 and women=138) participated in this study. The subjects were randomly separated into validation and cross-validation groups. Methods The whole-body impedance ( Z ) between the hands and feet was measured in the standing position. A stepwise multiple regression analysis was used to develop the prediction equation for SM mass. Whole-body SM mass, measured by magnetic resonance imaging (MRI), was used as a reference. Results BI index (height 2 / Z ), body surface area (BSA), gender, and age were selected as significant contributors to predict SM in the validation group. There was no significant difference between the measured and estimated SM mass and no systematic error in BI analysis in the cross-validation group. All data were pooled to generate the final regression equation: SM mass \( kg \) = \( 0.126 × BI index \) + \( 1.937 × BSA \) + \( − 0.062 × age \) + \( − 2.186 × gender \) − 2.881 , where age is in years. Gender for men=1 and women=2. Analysis revealed that the slope and intercept were not significantly different from one and zero, respectively. The r 2 and SEE values of the regression equation were 0.893 and 1.65kg, respectively. Conclusions Using our developed prediction equation, the BIA system can be used to accurately evaluate whole-body skeletal muscle mass with the subject in the standing position.