Electromyographic Analysis of the Femoral Muscle before and after a Mountain-climbing Race

[Purpose] This study aimed to identify the causes of muscle fatigue in the area surrounding the knee joints following a mountain-climbing race. [Subjects] Subjects were firefighters who competed in a Mount Fuji climbing race after performing regular training. [Methods] The strength and activity of the muscles surrounding the knee joints were measured prior to and following the climbing race. [Results] Whereas no significant changes were noted in knee joint extension/flexion torque values following the race, mean EMG frequencies and the RRE (Rate of Rise of absolute EMG amplitude) of the muscle action potential were significantly lower following the race. [Conclusion] The results suggest that there were decreases in muscle fiber conduction velocity and synchrony of motor unit action potential after the firefighters had competed in the climbing race. There were differences in mean EMG frequencies and the RRE depending on the muscle and angular velocity.