Concerning outfield players, FW players were next, followed by DF and MF (significantly lower than for DF and FW in concentric mode, Figs. 1 and 2). Not surprisingly, it seems logical that DF and FW developed more than MF due to their respective function during effort. However, all the differences disappeared when the results were corrected for body weight. At last, compared with results obtained by other researchers (Davis et al., 1992 and Cometti et al., 2000), the values of this study were higher at all the velocities.