Calf Venous Compliance During Hypotension After an Acute bout of Aerobic Exercise in Humans

Post-exercise hypotension (PEH) following prolonged dynamic exercise is induced by an increase in systemic vascular conductance via skeletal muscle vasodilation, which may occur not only in the arteries but also in the veins, and the vasodilated regions may contribute to greater venous pooling in the exercised limbs. However, the contribution of venous distention to PEH is unclear. Therefore, we aimed to evaluate venous compliance in previously exercised muscles in a preliminary study.

Seven participants performed a single 60-min session of upright cycle ergometry at 60% of heart rate reserve. Calf venous compliance was measured using venous congestion plethysmography before and 45 min following exercise in Trial 1. Stroke volume and femoral arterial blood flow were determined using ultrasonography at the same time points in Trial 2. Heart rate and blood pressure were monitored during both trials.

Mean arterial pressure significantly decreased between the start and ~ 30 min following the end of exercise (82 ± 6 mmHg vs. 76 ± 6 mmHg, respectively, in Trial 1; 79 ± 6 mmHg vs. 74 ± 5 mmHg, respectively, in Trial 2; P < 0.05). Pre- and post-exercise stroke volume did not significantly differ. Blood flow and vascular conductance in the femoral artery significantly increased from 641 ± 84 mL/min and 8.13 ± 0.79 mL/min/mmHg pre-exercise to 773 ± 121 mL/min and 10.55 ± 1.00 mL/min/mmHg post-exercise, respectively (P < 0.05). Pre- and post-exercise calf venous compliance did not significantly differ.

Our findings demonstrate that vasodilation in the active limb increases during exercise, but the resulting PEH does not affect venous compliance.