Differences in femoral artery blood velocity among active, inactive and passive recovery modes following knee extension and flexion exercise

The effect of the muscle pump on femoral artery mean blood flow velocity (MBV) was examined in five healthy men during 5 min of recovery following seated knee extension and flexion (KEF) exercise at 0.31±0.03% peak oxygen uptake(V̇O _2peak)for 5 min. The recovery was evaluated separately during three different activity modes: complete rest (inactive recovery), passively induced KEF(passive recovery), or voluntary KEF(active recovery) at 0.13±0.02% V̇O _2peak. The superficial MBV was measured beat-by-beat using a Doppler-ultrasound method. After exercise, the MBV temporarily increased within 5 sec followed by a rapid decrease and then a gradual decrease in all three recovery modes, but to different extents. The MBV at the 5th min was significantly higher in the active recovery mode, followed by the passive and inactive recovery mode, respectively. The change in total peripheral vascular resistance (TPR), calculated as the mean arterial blood pressure/ cardiac output(CO), was completely opposite to the change in MBV for each recovery mode. Both CO and V̇O ₂ decreased rapidly during the first minute followed by a gradual decrease, separately reaching either the unloaded exercise levels or the pre-exercise resting levels. The mean CO and V̇O ₂ at the 5th min were significantly greater for active recovery than for passive and inactive recovery. However, neither CO nor V̇O ₂ significantly differed between passive and inactive recovery. These data suggest that MBV during recovery from exercise increases in response to passive KEF without extra oxygen expenditure when compared with inactive recovery. This phenomenon is likely mediated by decreased TPR.