Fig. 4. (A) Toddlers' mean oscillations in E_p and E_k (± S.D.), are plotted as a function of gait cycle duration. The shaded bars indicate the double support phase. Both E_p as E_k show a sinusoidal oscillation with two maxima and two minima occurring during one gait cycle. The oscillations in E_p are largest and almost completely determine the total mechanical energy fluctuations. (B) The average kinetic energy fluctuations in the forward (y), lateral (x) and vertical (z) directions are plotted as a function of gait cycle duration. E_k is entirely determined by the forward kinetic energy fluctuations.