Fig. 6. The components of W_int,dc (W_f,front, W_f,back, W_v, W_back, W_front and W_com; in J kg^-1) are presented as a function of time during double contact (DC) for a slow speed step at 0.84 m s^-1 (A), a medium speed step at 1.37 m s^-1 (B) and a high speed step at 2.58 m s^-1 (C). The W_int,dc curve is obtained by subtracting instant-by-instant the positive increments in W_com from the positive increments in W_back and W_front (see Materials and methods). ⁺W_int,dc is the total increment in the W_int,dc curve (fine broken line) and is the work done by one leg against the other during DC. Note that the scale of the W_int,dc curve is 2.5 times that of the other curves. Other indications are as in Fig. 1. Data are from a 20.2-year-old 64.9 kg male subject.