Geert Kleinnibbelink

Post-Exercise Hypotension in Hypoxia 5 117 INTRODUCTION Post-exercise hypotension (PEH) is a reduction in systolic and/or diastolic arterial blood pressure (BP) below resting BP levels following a single bout of exercise and is usually observed minutes to hours after exercise. 1-3 The decline in BP after exercise relates to a marked decrease in total peripheral resistance (TPR) 3, 4 , due to sustained post-exercise local vasodilator mechanisms 5, 6 , with unmatched elevations in cardiac output. 7 The potential clinical relevance of PEH is that the magnitude of PEH relates to the BP-lowering effect of exercise training. 8-10 Enhancing the magnitude of PEH may, therefore, have the potential to increase the anti-hypertensive effects of exercise training. Previous research revealed that several factors, including exercise intensity 11-13 , duration 13, 14 , mode (interval or continuous 15 ), time of day 16 and body position 17 , may influence the magnitude of PEH. Relatively little work has examined the impact of hypoxia on PEH. This is relevant since previous work revealed that hypoxia contributes to a higher decrease in TPR post-exercise 18-20 potentially contributing to a larger PEH. Indeed, one previous study found a more profound PEH in response to resistance exercise under hypoxia versus normoxia. 21 Therefore, hypoxia may elicit a larger magnitude of PEH compared to normoxia. This is potentially relevant, since acute changes in BP with (hypoxic) exercise may relate to long-term changes in resting BP after regular exercise training. 8-10 A larger PEH in hypoxia may therefore translate into a larger decrease in resting BP, as previously suggested for normoxic exercise. 9 The aim of this study was 1) to investigate the influence of hypoxia versus normoxia on the PEHmagnitude of post-endurance exercise (high-intensity) in healthy individuals, and 2) whether the magnitude of PEH relates to the reduction in BP after a 12-week hypoxic endurance exercise-training program. According to previous research, we hypothesized that 1) high-intensity endurance exercise under hypoxia would elicit greater reductions in post-exercise BP compared to normoxia, and that 2) the magnitude of PEH would relate to the training-induced BP reduction.