Fig. 3

Symmetry indices (SI) as functions of walking speed and gradient for two types of prosthetic. The symmetry indices (dashed line) in non-amputees, previously reported in the literature are plotted for comparison (Minetti et al., 2011 [30]). Error bars have been omitted for clarity. Note that this Fig. highlights absolute speed rather than percentage of customary; the value plotted is the mean absolute speed for each category of relative customary speed category (0.8, 1, 1.2, 1.4 and 1.6 of customary speed: NB group mean customary speed was 0.98 m s^− 1)