Fig. 4. Representative regressions of electromyographic (EMG) variables on femoral adduction angle for hindlimb extensor muscles of individual experimental alligators. Larger angles indicate more upright posture, as illustrated by the sketches at the bottom of the figure. N=30 for both regressions. (A) Mean burst amplitude for the femorotibialis of Alligator 2 (=FEMTIB AREA DUR of Table 2). (B) Mean burst amplitude for the gastrocnemius of Alligator 4 (=GAST AREA DUR of Table 2). Burst amplitudes increase significantly with the use of upright posture for both muscles.