Figure 3.

Mean (SE) EMG signals for muscles acting to extend the ankle (MG and SOL) during the second half of stance normalized to the mean activity during level walking at 1.25 m·s⁻¹. Representative rectified EMG data are also provided for a single stride of one subject walking at 1.25 m·s⁻¹ on the level, uphill (+9°), and downhill (−9°), each on the same scale. Compared to level walking, muscle activity increased at all uphill grades for MG and steeper than 6° for SOL (p<0.0063). When walking downhill, muscle activity decreased at all grades for MG, and for grades steeper than 6° for SOL. Note: 1.25 and 1.75 m·s⁻¹ points are shifted slightly to the right for clarity. * Significantly different from level walking across speeds according to post-hoc comparisons with Bonferroni adjusted level of significance (p < 0.0063).