The purpose of this study was to compare the effects of active vs. passive recovery on the time to exhaustion for intermittent runs (15 s) at supramaximal velocity (120% of maximal aerobic speed). Twelve male subjects performed a graded test, an intermittent run to exhaustion with active recovery (50% of maximal aerobic speed) and an intermittent run to exhaustion with passive recovery. Results showed that intermittent runs to exhaustion with passive recovery [745 (171) s] allowed subjects to run for a significantly longer (p<0.001) time than intermittent runs to exhaustion with active recovery [445 (79) s]. These results could be explained by a significantly higher (p<0.001) energy requirement for intermittent runs with active recovery [59.9 (9.6) ml.kg(-1).min(-1)] than for intermittent runs with passive recovery [48.9 (6.9) ml.kg(-1).min(-1)]. It could be also hypothesized that the energy required to run during short active recovery would result in less oxygen being available to reload myoglobin and haemoglobin, to remove lactate concentrations and to resynthesize the phosphocreatine. Consequently, for intermittent runs with short recovery periods, passive recovery will induce a longer time to exhaustion than active recovery.