Hypoxic exercise training improved aerobic capacity and ameliorated the suppression of cardiac stroke volume and muscle hyperemic response during acute severe hypoxia compared to normoxic exercise.
RCT (n=60)
Randomly divided
Does hypoxic exercise training improve cardiac, muscular, and cerebral hemodynamics during severe hypoxic exposure in sedentary males?
Moderate hypoxic exercise training improves cardiopulmonary fitness and increases resistance to disturbance of cardiac hemodynamics by severe hypoxia, while enhancing oxygen delivery and utilization in skeletal muscles.
Hypoxic preconditioning prevents cerebrovascular/cardiovascular disorders by increasing resistance to acute ischemic stress, but severe hypoxic exposure disturbs vascular hemodynamics. This study compared how various exercise regimens with/without hypoxia affect hemodynamics and oxygenation in cardiac, muscle, and cerebral tissues during severe hypoxic exposure. Sixty sedentary males were randomly divided into five groups. Each group (n = 12) received one of five interventions: 1) normoxic (21% O(2)) resting control, 2) hypoxic (15% O(2)) resting control, 3) normoxic exercise (50% maximum work rate under 21% O(2); N-E group), 4) hypoxic-relative exercise (50% maximal heart rate reserve under 15% O(2); H-RE group), or 5) hypoxic-absolute exercise (50% maximum work rate under 15% O(2); H-AE group) for 30 min/day, 5 days/wk, for 4 wk. A recently developed noninvasive bioreactance device was used to measure cardiac hemodynamics, and near-infrared spectroscopy was used to assess perfusion and oxygenation in the vastus lateralis (VL)/gastrocnemius (GN) muscles and frontal cerebral lobe (FC). Our results demonstrated that the H-AE group had a larger improvement in aerobic capacity compared with the N-E group. Both H-RE and H-AE ameliorated the suppression of cardiac stroke volume and the GN hyperemic response (Delta total Hb/min) and reoxygenation rate by acute 12% O(2) exposure. Simultaneously, the two hypoxic interventions enhanced perfusion (Delta total Hb) and O(2) extraction Delta deoxyHb of the VL muscle during the 12% O(2) exercise. Although acute 12% O(2) exercise decreased oxygenation (Delta O(2)Hb) of the FC, none of the 4-wk interventions influenced the cerebral perfusion and oxygenation during normoxic/hypoxic exercise tests. Therefore, we conclude that moderate hypoxic exercise training improves cardiopulmonary fitness and increases resistance to disturbance of cardiac hemodynamics by severe hypoxia, concurrence with enhancing O(2) delivery/utilization in skeletal muscles but not cerebral tissues.
Wang et al. (Fri,) conducted a rct in Sedentary (n=60). Hypoxic exercise regimens (H-RE and H-AE) vs. Normoxic resting, hypoxic resting, and normoxic exercise was evaluated on Hemodynamics and oxygenation in cardiac, muscle, and cerebral tissues during severe hypoxic exposure. Hypoxic exercise training improved aerobic capacity and ameliorated the suppression of cardiac stroke volume and muscle hyperemic response during acute severe hypoxia compared to normoxic exercise.