Since leg muscles receive the majority of cardiac output and consume a large proportion of total oxygen consumption (˙VO2) during cycle exercise, maximum leg blood flow may be an important determinant of peak˙VO2 (˙VO2peak). We investigated the relationships between parameters of active hyperemia after thigh tourniquet occlusion (alone or with calf exercise) with whole body peak exercise capacity during maximum cycle exercise. Twenty-one healthy male subjects, aged 19-39 yr, performed maximum incremental cycle exercise. Calf blood flow, conductance (blood flow/mean blood pressure), vasodilatory capacity (peak/baseline conductance), and duration of vasodilation were then determined with venous occlusive plethysmography under two conditions: 1) after thigh tourniquet occlusion for 10 min; 2) after ischemic calf exercise (thigh tourniquet occlusion with calf exercise to exhaustion). Group mean ˙VO2peak was 120 ± 35%(standard deviation) predicted. There was a significant relationship between˙VO2peak/lean body mass and peak calf conductance after maximum ischemic calf exercise (r = 0.556; P < 0.01). However,˙VO2peak/lean body mass was more closely correlated with the duration of vasodilation after thigh tourniquet occlusion with ischemic calf exercise (r = 0.861; P < 0.001). These results suggest that the duration of calf vasodilation after maximal ischemic calf exercise appears to be a better index of cycle exercise capacity in healthy subjects.