Repetitive Bimanual Force Control and Tensiomyography-Derived Muscle Contractile Properties

Lee, JH, Yeom, S, Jeon, K, and Kang, N. Repetitive bimanual force control and tensiomyography-derived muscle contractile properties. J Strength Cond Res XX(X): 000-000, 2026-Repetitive muscle contractions may induce progressive neuromuscular fatigue, affecting bimanual force control and muscle contractile properties. We investigated changes in bimanual force control strategies and tensiomyography (TMG)-derived muscle contractile properties during a repetitive isometric handgrip task. Fifteen healthy right-handed individuals performed repetitive bimanual force control trials at 40% of the maximum voluntary contraction until task failure. Force variability (i.e., coefficient of variation) and regularity (i.e., sample entropy) were quantified across the initial, middle, and terminal trial phases. Using TMG, we assessed the contractile properties of the flexor digitorum superficialis muscle in dominant and nondominant hands before and after the task. The subjects exhibited increasing bimanual force variability and regularity from the initial to the terminal trial phases ( p < 0.001). The dominant hand exhibited lower force regularity than the nondominant hand across the three trial phases ( p = 0.021). TMG findings showed decreased delay time in the nondominant hand ( p < 0.001), reduced contraction time in both hands ( p < 0.001), and increased contraction velocity in the dominant hand ( p = 0.006), indicating faster contraction responses. Correlation analysis indicated that increased delay time in the dominant hand at baseline was related to more successful trials ( p = 0.027) and decreased force variability ( p = 0.003) and regularity ( p = 0.027) in the middle trial phase. These findings suggest asymmetrical neuromuscular adaptations between the hands, with increasing dominant hand reliance during fatiguing bimanual contractions. This insight may help guide optimized neuromuscular training strategies for addressing fatigue-related asymmetries and injuries.