Fig. 7. Mean peak muscle stress for the LG and MG walking (black; 0.5 m s^–1) and running (grey; 2.0 m s^–1) on a level (left pair of bars) and inclined (right pair of bars) treadmill. Note that muscle force and stress increased with running speed on the level and inclined treadmill for both muscles, but force and stress were not affected by incline. Values are means ± s.e.m. (N=4).