Fig. 5.

Mean swing duration before, during, and after discrete ankle perturbation for three walking speeds. R: reference swing duration taken from strides immediately before perturbation, P: perturbed stride, 1–6: strides following perturbation. TOP: perturbations that occurred in early swing resulting in a lengthening of the swing phase. BOTTOM: perturbations that occurred in late swing resulting in a shortening of the swing phase. Bars represent standard error of the mean.