Change in telescoping leg strategy with varying walking speed to modulate force advantage

Human walking consists of two major sequential events (i.e., single- and double-support phases). Although there have been many studies relating to basic principles of the each stage, how the two distinct but continuous phases interact with each other remains to be clarified. We examined the change in walking strategy with varying walking speed on a local reference frame with telescoping and tangential axes; we expect that the telescoping directional dynamics at the end of a single-support phase change with walking speed to facilitate the modulation of the push-off work during a double-support phase. The telescoping directional force and power are calculated using two methods: model simulation and kinematic configuration. The empirical walking data for eight healthy young subjects and the corresponding model parameters obtained from a data-fit optimization were used to investigate the changing trend of each factor (i.e., force and power) with the increase in speed. The resulting force at the end of the single-support phase significantly increased with the walking speed for both methods, whereas the resulting power remained nearly unchanged and was close to zero for the entire range of walking speeds. This result implies that the positive amount of the telescoping directional force at the end of the single-support phase may be a certain type of preparation for the double-support phase, which can contribute to a larger push-off.