The purpose of this study was to determine the neuromuscular and metabolic changes among three selected preferred transition speeds (PTS) and two types of gait (walk and run). Twelve male subjects were enrolled to participate in this study. Vicon® motion capture system, Biopac® Electromyography and Cosmed® Indirect Calorimeter were used to determine the kinematics, neuromuscular control and metabolic expenditure, respectively. Subjects were asked to walk and run repeatedly under three different speed (75, 100, 125% PTS). The results show that thigh/shank iEMG ECC/CON ratio illustrates the metabolic change among different PTSs. A significant inefficient shank muscle activation was initially occurred under 100% PTS, furthermore thigh muscle became inefficient under 125% PTS. It is suggested that "muscle elastic capacity" may contribute to the changes in muscle activation between walking and running under different PTSs. During walking, the increase in walking speed may lead to decreased utilization of muscle elastic energy, whereas it is opposite the case for running. This study provides a different approach to clarify the unexplored area between physiological and neuromuscular system on PTS.
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