Multivariate Analysis of the Relationships among Muscle Strength, Muscle Endurance, and Muscle Oxygenation Dynamics During Incremental Exercise

OBJECTIVE: We aimed to clarify whether having both high leg muscle strength (MS) and leg muscle endurance (ME) contributes to optimal muscle oxygenation dynamics during incremental exercise, regardless of related factors. DESIGN: A prospective cross-sectional study. Thirty healthy young individuals were categorized into low leg MS (Low-MS group: n=15), high leg MS but low leg ME (High-MS/Low-ME group: n=8), and both high leg MS and leg ME (High-MS/High-ME group: n=7) groups. Muscle oxygen saturation (SmO2) at the vastus lateralis was measured during incremental exercise. Whole-body oxygen uptake (VO2), total hemoglobin (THb) at the vastus lateralis, sex, leg muscle mass, and adipose tissue thickness (ATT) were considered related factors. RESULTS: The multivariate mixed regression model, with SmO2 change from rest to 30-100% peak VO2 as the dependent variable; individual as a random effect; and sex, group, leg muscle mass, ATT, THb change from rest to 30-100% peak VO2, and peak VO2 as fixed effects, revealed that group (High-MS/High-ME group vs. High-MS/Low-ME group) significantly predicted SmO2 change from rest to 30-100% peak VO2 (estimates=26.2, P<0.001). CONCLUSION: Having both high leg MS and ME may contribute to optimal leg muscle oxygenation dynamics during incremental exercise, regardless of related factors.