Fig. 3. Principal component loading scores for PC I and PC II during walking and running for the leg flexors. Each point shows the mean ± S.E.M. loading scores pooled from the six subjects (N>348). The 20 points on each graph show the PC loading scores at the 20 successive time-windows during each stride, graded from black immediately after heel-strike to light grey immediately before the next heel-strike. Data are shown for the biceps femoris (A), the semitendinosus (B) and the tibialis anterior (C).