Figure 8.

Moment arm profiles of (A,B) the biceps femoris posterior, (C,D) biceps femoris anterior, and (E,F) plantaris as calculated about their spanned joints over a physiological walking profile. Muscle moment arm length travels along the outside of the surface over the step cycle. Projections of the profile are shown to the side, representing the profile shape for a single joint motion. Arrows indicate the development of the moment arm over the step cycle, and colored dots represent touch down (red) and lift off (green). Joint angles follow the zero-angle conventions established by Johnson et al. [17] and Charles et al. [18].