EFFECTS OF DYNAMIC FATIGUE ON RATE OF VELOCITY AND TORQUE DEVELOPMENT IN MALES AND FEMALES
Anna G. Conroy, Phuong L. Ha, Benjamin E. Dalton, Michaela G. Alesi, Tyler M. Smith, Trisha A. VanDusseldorp, Yuri Feito, Garrett M. Hester. Kennesaw State University, Kennesaw, GA 30144
Time-dependent measures such as rate of velocity (RVD; Δvelocity/Δtime) and torque (RTD; Δtorque/Δtime) development are important contributors to peak power during a dynamic muscle contraction. However, sex differences in the fatigability of these parameters remain relatively unexplored. Purpose: To determine sex differences for RVD and RTD of the plantar flexors (PFs) during a dynamic fatiguing task. Methods: Recreationally active males (n=14; 22.4±2.2 yrs) and females (n=15; 20.9±2.5 yrs) performed a fatiguing task of the PFs consisting of 60 maximal concentric isotonic contractions at 30% of their maximal isometric strength using a dynamometer. RVD and RTD were obtained from the first five contractions of the fatigue task and five maximal isotonic contractions performed after the fatigue task. Strong verbal encouragement was provided, and participants were instructed to perform the muscle contractions “as hard and fast as possible”. RVD and RTD were calculated as the linear slope of the velocity- and torque-time curve, respectively. Two-way (time ´ sex) repeated measures ANOVAs were used to determine sex differences across time. Results: Regardless of sex, RVD was decreased (-14%; p\u3c0.001), however, RTD was reduced in males (-18%; p=0.001) but not females (-8%; p=0.162) following the fatigue protocol. Conclusions: These data indicate that fatigue-induced decrements in quick velocity and torque production during dynamic exercise are different between sexes. Females appear to preserve the ability to produce torque quickly better than males in a fatigued state.
Keywords: Fatigue, sex differences, skeletal muscle, powe
