The acute effects of exercise intensity and inorganic nitrate supplementation on subendocardial viability ratio in postmenopausal females

Background: Menopause elevates coronary heart disease (CHD) risk partly due to reduced estrogen-derived nitric oxide (NO) bioavailability. Coronary artery perfusion is a predictor of CHD and subendocardial viability ratio (SEVR) reflects the balance of myocardial oxygen supply and demand as an indicator of myocardial perfusion. Postmenopausal females (PMF) exhibit a lower SEVR and impaired myocardial perfusion compared to age-matched males. Although exercise can benefit myocardial perfusion, there appears to be a transient reduction in SEVR following acute exercise and endothelial-training adaptations are blunted in PMF. We recently reported that acute high-intensity exercise with inorganic nitrate (NO 3 - ) supplementation increased NO bioavailability and improved post-exercise endothelial function in PMF, but the impact of acute exercise and NO 3 - on myocardial O 2 supply and demand (SEVR) remains unexplored. Hypothesis: Following acute exercise, SEVR in PMF will be reduced in an exercise-intensity dependent manner and will be attenuated with NO 3 - supplementation. Methods: In a double-blinded, randomized design, 24 PMF (60±5 years, 27.5±5.9 kg/m 2 , 10±5 years since menopause, VO 2 peak=1.7±0.3 L/min) were randomized to consume 13 mmol of NO 3 - in the form of beetroot juice (BRJ; n=12) or placebo (PL; n=12) for 2 days with the last dose 2h before testing. SEVR was noninvasively measured via pulse wave analysis (SphymoCor, AtCor Medical) before (T0) and at 30 min intervals after (T60, T90, T120, T150, and T180) calorically matched high-intensity exercise (HIE), moderate-intensity exercise (MIE), and a non-exercise control (CON). Venous blood was sampled prior to supplementation and at rest 2h after the last supplementation dose for plasma NO 3 - and nitrite (NO 2 - ) concentrations. The area under the curve (SEVR AUC) was calculated for treatment group and exercise intensity. Mixed-model ANOVAs were performed to compare post-exercise SEVR across intensities and treatments. Results: BRJ supplementation significantly increased plasma NO 3 - (BRJ: 999±207mM; PL: 48±20mM; p<0.001) and plasma NO 2 - (BRJ: 544±241nM; PL: 200±132nM; p <0.001). Post-exercise SEVR AUC was significantly decreased compared to CON in an intensity dependent manner (intensity effect: p <0.0001). The BRJ treatment group had a significant attenuation in the post-exercise SEVR AUC decline compared to PL (treatment effect: p =0.009). Post hoc analysis showed the BRJ-induced attenuation in post-exercise SEVR AUC was significant following HIE (PL: 21,938±993 AU vs BRJ: 24,437±1,367AU, p<0.0001). Conclusions: Acute exercise suppresses SEVR for several hours in PMF in an intensity dependent manner, suggesting impaired myocardial O 2 supply to demand. NO 3 - supplementation attenuated the decline in post-exercise SEVR in healthy PMF. This work was supported by the UVA School of Education and Human Development Inclusion Diversity Equity Access (IDEA) and the UVA Department of Kinesiology (AW). This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.