Fig. 6. A comparison of the movement of the modeled load (thick red line) with the movement of the body in the two longer frog jumps shown in Fig. 2 (thin blue and black lines). Each column of graphs presents the velocity, force and power of the load/body for a single contraction under one of four model configurations: (A) no series elastic element, constant effective mechanical advantage (EMA), (B) no series elastic element, decreasing EMA, (C) compliant series elastic element, constant EMA and (D) compliant series elastic element, increasing EMA. The shape of the force, velocity and power curves during jumping in frogs most closely resembles the model configuration shown in D, where the muscle actuator contracts through a series elastic element and a continuously increasing EMA. All model contractions occurred over the same total muscle strain and same total load displacement. Power is expressed in W kg^-1 body mass.