Fig. 2.

Comparison of ground forces between model and experiment. (A) Ground forces measured during the stance phase of level running and following a drop in terrain (14). (B) Schematic of the hypothesized mass–spring model (Eqs. 1–3). (C) By adjusting only one parameter, leg contact angle (ϕ_o), the model predicts ground forces that are similar in magnitude and time course to those measured experimentally. Modeled forces were obtained through numerical integration of Eqs. 1 and 2.