RELATIONSHIP BETWEEN ANKLE PLANTAR FLEXOR POWER AND EMG MUSCLE ACTIVITY DURING GAIT

It is thought that the A2 ankle power burst observed in human gait is solely generated by rapid concentric contraction of the ankle plantar flexors. Recent work, however, suggests that the return of elastic energy may play a role. This study investigated the temporal relationship between the maximum electromyographic activity (EMG) of the ankle plantar flexors and A2. The natural gait of eight young adults were recorded across level ground. Collectively, the maximum EMG of the Soleus, Gastrocnemius and Peroneus Longus fell 92 ms before A2. The period between maximum EMG and A2 were longer than the electromechanical delay reported in the literature (e.g. 8 to 45 ms). It is reasonable to conclude, therefore, that it may be partly produced by the return of elastic energy stored in the musculotendinous units of the plantar flexors during the A1 absorption period.