Abstract P070: Vascular Conditioning Exercise Acutely Enhances Endothelial Function In Young Adults

Abstract

Introduction: Vascular conditioning exercise (VCE), otherwise known as high-resistance inspiratory muscle strength training, is a potent non-pharmacological therapy to reduce blood pressure. When performed daily for 6 weeks, systolic blood pressure is reduced by ~6-10 mmHg on average, in part, by increasing nitric oxide-mediated endothelial dependent dilation (EDD). While the adaptations to long-term VCE have been described, the acute effects of VCE that may mediate the long-term vascular adaptations have not been thoroughly investigated. Hypothesis: We assessed the hypothesis that a single bout of VCE would increase EDD for at least 40 minutes after exercise completion, while arterial stiffness would not be affected. Methods: Nitric oxide-mediated EDD and ischemia-induced maximal shear rate were assessed with brachial artery flow-mediated dilation, and arterial stiffness was assessed via carotid-femoral pulse wave velocity. Assessments were performed before, 10 minutes after, and 40 minutes after a single bout of VCE (5 sets of 6 breaths at 50% of maximal inspiratory pressure with 1-minute rest intervals) or a time-matched rest interval in nine young adults (22.3 ± 2.6 years; 3 male, 6 female) using a randomized crossover design, with at least 48 hours between visits. Results: All values are mean difference ± SD. There were no differences between interventions in EDD at baseline (0.73 ± 3.7%; p =0.569). EDD was significantly higher 10 minutes post-VCE, relative to the rest intervention (3.28 ± 3.37%; p = 0.019), but there were no differences at 40 minutes post-intervention (0.01 ± 4.46%; p =0.992). Further, there were no differences in maximal shear rate between measurements (all p -values >0.05), indicating the changes in EDD were not due to a modified hyperaemic response. Lastly, there were no differences in arterial stiffness (Baseline: 0.22 ± 0.75 m/s; Post-10: 0.26 ± 0.51 m/s; Post-40: 0.27 ± 0.33 m/s; all p -values >0.05). Conclusions: A single bout of VCE transiently enhances EDD in healthy young adults, although this effect disappears within 40 minutes of exercise completion. This acute functional response to VCE can partially explain the large improvements in EDD that are seen in response to daily VCE performance over longer periods.