Vascular adaptations to hypobaric hypoxic training in postmenopausal women

Abstract

The objective of this study was to examine the effects of exercise training in hypoxia on arterial stiffness and flow-mediated vasodilation (FMD) in postmenopausal women. Sixteen postmenopausal women (56±1 years) were assigned to a normoxic exercise group (Normoxic group, n=8) or a hypoxic exercise group (Hypoxic group, n=8). The Hypoxic group performed exercise under hypobaric hypoxic conditions corresponding to 2000 m above sea level, and was exposed to these conditions for 2 h per session. Aquatic exercise was performed at an intensity of around 50% peak oxygen uptake for 30min, 4days per week, for 8 weeks. Arterial stiffness was assessed by brachial-ankle pulse wave velocity (baPWV), and FMD was evaluated by peak diameter of the popliteal artery during reactive hyperemia. After the 8 weeks of training, the Normoxic group showed no significant changes. In contrast, baPWV (P < 0.05) was significantly reduced and peak diameter (P<0.05) and %FMD (P<0.01) were significantly increased in the Hypoxic group after training. These results suggest that exercise training under mild intermittent hypoxic conditions could more effectively reduce arterial stiffness in postmenopausal women, compared with exercise training performed at the same relative intensity under normoxic conditions. Our data also indicate that hypoxic exercise training may induce vascular functional adaptation, for example an increase in FMD response. These findings therefore could have important implications for the development of a new effective exercise prescription program.

Fig. 1

Changes in brachial–ankle pulse wave velocity (baPWV) before and after exercise training. Closed circles represent change in baPWV for each individual value in Normoxic and Hypoxic groups. Open circles represent change in baPWV for mean values before and after exercise training. Vertical bars indicate standard error of the mean

Fig. 2

Changes in diameter of popliteal artery and %FMD before and after exercise training. a Diameter of popliteal artery at rest. b Peak diameter during reactive hyperemia. c %FMD (%FMD was calculated as the percentage rise of the peak diameter from the preceding diameter at rest). Vertical bars indicate standard error of the mean