http://worldcat.org/entity/work/id/40371534

The role of musculoskeletal forces in the human walk-run transition

This investigation examined the possible role of musculoskeletal forces in the human walk-run transition. In order to measure these forces a treadmill was constructed which allowed the measurement of vertical ground reaction forces while subjects walked and ran at prescribed speeds. Validation proved the device to be accurate and reliable in measuring the midstance vertical ground reaction forces which were analyzed in this study. Ten untrained runners were recruited from the University population and paid for their participation in this study. To differentiate the roles of speed of locomotion and musculoskeletal force, both speed and subject weight were manipulated. Speed was controlled by the treadmill operator and weight was added to the subjects in the form of a weight vest of approximately 15% body weight. Each subject's preferred transition speed was determined for the weighted and unweighted conditions. Following this determination, each subject's midstance vertical ground reaction forces were measured while walking and running over a range of speeds for both weight conditions. The force at transition was consistent for the two conditions for the subjects measured, indicating that musculoskeletal force may have a role in the transition. However, speed of transition was also consistent, not allowing differentiation of the two variables. Mapping the midstance forces of each gait versus speed of locomotion illustrated running to have a significant increase in force at the preferred transition speed. A trend of increasing variability of force at and above the preferred transition speed was evident for walking. This instability may facilitate or prompt the change from walking to running. As a result of this investigation, musculoskeletal forces may be considered to have some influence on the human walk-run transition.

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