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

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.
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