Fig. 7. Mean muscle force and net work per stride against relative electromyographic (EMG) intensity for lateral gastrocnemius (LG, left) and digital flexor-4 (DF-IV, right), during locomotion on the level (open circles) and incline (filled squares). For clarity, results are shown for one representative individual (bird 3); however, the pattern of change from level to incline was similar across individuals, as indicated by the mean slopes and r² values given in the text.