Fig. 8.

Average normalized fiber length () and period of highest activation of 11 muscles during gait at four walking speeds and four running speeds (N=5). Colors indicate gait speed in walking (1.00–1.75 m s⁻¹) and running (2.00–5.00 m s⁻¹). Thick horizontal lines indicate portions of the gait cycle when a muscle's activation exceeded 80% of the maximum value for that speed. Vertical lines on the abscissa indicate the instant of toe off for each of the eight speeds. Thin grey lines bound the plateau of the force–length curve, where normalized fiber length is between 0.95 and 1.05.