Fig. 3. Relationships between peak muscle force and root mean squares of electromyographic activity (EMG) for MG and SOL for (A) cat 1, (B) cat 2, (E) cat 5, (F) cat 6 and (G) cat 7. (C,D) Cats 3 and 4, for which no SOL forces were available. The group `level+treadmill' includes all data from level and treadmill walking (0.4-1.2 m s^-1).