Fig. 2. Group mean vertical (A) and anterior–posterior (B) ground reaction forces (normalized to body weight, BW) during walking with stride rates above (+20%), below (–20%), and at the preferred rate. The ±10% conditions have been omitted for clarity, but were generally intermediate to the preferred and ±20% conditions. At higher stride rates there were greater fluctuations in the vertical force, reduced peak anterior-posterior forces, and the stance phase lasted a greater proportion of the gait cycle. Zero and 100% of the gait cycle correspond to right heel strike, and the end of the stance phase coincides with the forces going to zero.