An electromyographical analysis of the role of dorsiflexors on the gait transition during human locomotion

Previous research has demonstrated that the preferred transition speed duri ng human locomotion is the speed at which critical levels of ankle angular velocity and acceleration (in the dorsiflexor direction) are reached, leadi ng to the hypothesis that gait transition occurs to alleviate muscular stre ss on the dorsiflexors. Furthermore, it has been shown that the metabolic c ost of running at the preferred transition speed is greater than that of wa lking at that speed. This increase in energetic cost at gait transition has been hypothesized to occur due to a greater demand being placed on the lar ger muscles of the lower extremity when gait changes from a walk to a run. This hypothesis was tested by monitoring electromyographic (EMG) activity o f the tibialis anterior, medial gastrocnemius, vastus lateralis, biceps fem oris, and gluteus maximus while participants (6 M, 3 F) walked at speeds of 70, 80, 90, and 100% of their preferred transition speed, and ran at their preferred transition speed. The EMG activity of the tibialis anterior incr eased as walking speed increased, then decreased when gait changed to a run at the preferred transition speed. Concurrently, the EMG activity of all o ther muscles that were monitored increased with increasing walking speed, a nd at a greater rate when gait changed to a run at the preferred transition speed. The results of this study supported the hypothesis presented.