Intra-stride belt-speed variation affects treadmill locomotion

For overground and treadmill locomotion to be mechanically similar, it is required that the belt speed of the treadmill is constant and the same to that of overground locomotion. Variation of the belt speed during a stride causes exchange of energy between the subject and the treadmill. This might be the cause of different kinematic patterns between overground and treadmill locomotion, which have been reported in literature. The aim of this study was to investigate whether the intra-stride belt-speed is variable, and whether differences in kinematic patterns can be attributed to these variations. Nine subjects walked and ran overground and on two treadmills that were differently susceptible to subjectsʹ braking and accelerating forces. It was found that the speed variations during treadmill locomotion affect the kinematic parameters significantly. The amount of intra-stride belt-speed variation was found to depend on the power of the treadmill and the mass of the subject.