Hypoxic Exercise Training Enhances Vascular Hemodynamics and Oxygen Utilization in Skeletal Muscles

Abstract

This study investigates how hypoxic exercise training impacts on vascular hemodynamic and O2 utilization in exercising skeletal muscles. Twelve sedentary males were trained on a bicycle ergometer at about 60%VO2max under 15% O2 air condition for 20 minutes per day, 5 days per week for 4 weeks. Vascular hemodynamics and O2 consumption and re‐oxygenation rate in gastrocnemius were determined by near infrared spectroscopy. Our results showed that 4 weeks of hypoxic exercise training improved subjects' aerobic fitness at ventilation threshold and maximal performance. Acute exposure to 12%O2 decreased arterial hyperemia and venous compliance, as well as, oxygen consumption and re‐oxygenation rate in gastrocnemius at pre‐training state. However, the suppressive effects in vascular hemodynamics and tissue O2 utilization in gastrocnemius by acute hypoxic exposure were ameliorated following the hypoxic exercise training. Therefore, we conclude that long‐term hypoxic exercise training can improve cardiopulmonary fitness and increase the tolerance to hypoxia‐limited O2 transport and utilization in skeletal muscles.