Fig. 2. Gait elements within stance phase for a typical stride. (A) Midstance elements were defined as follows: foot strike is the first kinematic frame in which the foot (labeled by the TPj kinematic marker) contacts the trackway; foot off is the first kinematic frame in which the foot rises from the trackway; toe off is the first frame in which the foot begins a second, larger arc about the tip of the phalanges; swing phase is the first frame of swing phase. Adapted from Gatesy (1999). (B) The timing of midstance elements relative to peak nGRF for 16 strides. Mean occurrence time for each gait element is indicated; values are means ± s.e.m. Negative times indicate the element occurred before peak nGRF, while positive times indicate it occurred after. Foot off was coincident with peak nGRF (mean difference 0±0.01 s, N=16 strides).