Fig. 5. The lower support of the body during the downward displacement of the centre of mass relative to upward displacement is indicated on the ordinate by a ratio R_int,down/R_int greater than 0.5 at all running speeds (abscissa). Note that R_int is the cumulative value at the end of the step of the instantaneous E_k–E_p transduction: data show that the transduction of E_p into E_k during the downward displacement is greater than the transduction of E_k into E_p during the upward displacement [see R_int(t) curve in Fig. 7]. Statistics as in Fig. 2.