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 50kHz 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 (13.6º ± 1.5º vs. 11.5º ± 1.5º, 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.