Hypoxic Exercise Training Improves Cardiac and Muscular Hemodynamics by Modulating Circulating Progenitor Cells in Sedentary Men

Abstract

This study investigated whether exercise regimens with/without hypoxia affect cardiac and muscular hemodynamics by modulating circulating progenitor cells (CPCs) and angiogenic factors. Forty sedentary males were randomly divided into hypoxic (HT, n=20) and normoxic (NT, n=20) training groups. The subjects were trained on a bicycle ergometer at 60% VO2max under 15% (HT) or 21% (NT) O2 conditions for 30 minutes daily, five days weekly for five weeks. After the interventions, the HT group exhibited a larger improvement in aerobic capacity than the NT group. Furthermore, the HT regimen (i) enhanced cardiac output (QH) and perfusion (QM)/oxygenation of vastus lateralis during exercise; (ii) increased the levels of circulating hematopoietic progenitor cell (HPC) and endothelial progenitor (EPC)/precursor (CEP) cells; (iii) promoted the proliferative capacity of these CPC subsets, and (iv) elevated plasma nitrite/nitrate, stromal cell‐derived factor‐1, matrix metalloproteinase‐9, and vascular endothelial growth factor‐A concentrations. Despite the lack of changes in QH and the number/proliferative capacity of HPC or CEP, the NT regimen elevated both QM and plasma nitrite/nitrate levels and suppressed the shedding of endothelial cells. We conclude that the HT regimen improves cardiac and muscular hemodynamic adaptations, possibly by promoting the mobilization/function of CPCs and the production of angiogenic factors.