Is muscle localized phase angle an indicator of muscle power and strength in young women?

Abstract

Objective. This study aimed to investigate the capacity of the bioelectrical muscle localized phase angle (ML-PhA) as an indicator of muscle power and strength compared to whole body PhA (WB-PhA). Approach. This study assessed 30 young women (22.1 ± 3.2 years) for muscle power and strength using the Wingate test and isokinetic dynamometer, respectively. Bioimpedance analysis at 50 kHz was employed to assess WB-PhA and ML-PhA. Lean soft tissue (LST) and fat mass (FM) were quantified using dual x-ray absorptiometry. Performance values were stratified into tertiles for comparisons. Regression and mediation analysis were used to test WB-PhA and ML-PhA as performance predictors. Main results. Women in the second tertile of maximum muscle power demonstrated higher ML-PhA values than those in first tertile (13.6° ± 1.5° versus 11.5° ± 1.5°, p = 0.031). WB-PhA was a predictor of maximum muscle power even after adjusting for LST and FM (β = 0.40, p = 0.039). ML-PhA alone predicted average muscle power (β = 0.47, p = 0.008). FM percentage was negatively related to ML-PhA and average muscle power, and it mediated their relationship (b = 0.14; bias-corrected and accelerated 95% confidence interval: 0.007–0.269). Significance. PhA values among tertiles demonstrated no differences and no correlation for strength variables. The results revealed that both WB and ML-PhA may be markers of muscle power in active young women.