FIGURE 3.

Simulation results for single lower extremity extensions of model A1. A, Time history of vertical velocity during the push-off for an unloaded jump (v) and for an isokinetic contraction at the average speed ( $\overline{v}$). Note that we calculated the true $\overline{v}$ for the jump, which was 1.42 m·s⁻¹; approximating $\overline{v}$ by taking half the takeoff velocity in the jump (2,3) would have yielded a value of only 1.15 m·s⁻¹ in this case. B, Vertical displacement during the push-off (Δh_PO) for corresponding lower extremity extensions. C, Velocity plotted as a function of Δh_PO. D. Vertical force (F) plotted as a function of Δh_PO. During an isokinetic contraction at the average velocity of the jump ( $\overline{v}$), more effective work is done (area below F ( $\overline{v}$)) than during the jump (gray area). At isokinetic velocity v* (higher than $\overline{v}$, see C), the same amount of work is done as during the jump.