Figure 4.

Activation sweep. (a) Work and (b) power outputs from dynamic oscillations of stimulated muscle 137 in the intact-joint work loop preparation showed primarily energy absorbing outcomes as activation was increased. Increasing cycle frequency (8 Hz stride frequency; light grey bars) from those of past studies [11] to the stride frequency observed in our in vivo experiments (11 Hz stride frequency; dark grey bars) increased energy absorption. Intact-joint work loops using the same parameters as previously published [11] isolated muscle work loops produced statistically indistinguishable work and power (bars marked with §).