Fig.5. (A) Electromyographic trace from the vastus lateralis of the trailing limb from a rat during level galloping. (B) An expanded view of two cycles of EMG activity showing an initial small burst of vastus activity late in the swing phase followed by a larger burst of activity commencing near the onset of the stance phase (demarcated by the vertical line separating the light and dark shading). The initial bursts of activity late in the swing phase were always of much lower intensity than the stance-related bursts and have been discussed in some detail previously (de Leon et al., 1994).