Purpose: The increase in blood pressure (BP) levels in the postmenopausal period can be partly explained by the decrease in nitric oxide synthases (NOS). Dietary nitrate (NO3) can increase NO production regardless of endothelial NOS activity and, therefore, can counteract the low bioavailability of NO in circulation from the endogenous pathway. The objective was to investigate the acute and one-week effects of beetroot juice nitrate-rich (BRJ-NO3rich) ingestion on cardiovascular and autonomic performance in response to submaximal aerobic exercise in postmenopausal women with systemic arterial hypertension (SAH) who are physically inactive.
Methods: Fourteen postmenopausal women with SAH [mean (SD) age: 59(4) y; BMI (kg/m2): 29.2(3.1)] completed submaximal aerobic exercise bouts after an acute and a one-week intervention with BRJ in a placebo-controlled, randomized, triple-blind, crossover design. Participants ingested either BRJ (800mg of NO3) or placebo acutely and drank either BRJ (400mg of NO3) or placebo every day for the next six days. After two and ½ hours, they performed a session of aerobic submaximal aerobic exercise, and their systolic BP (SBP) and diastolic BP (DBP), flow-mediated dilation (FMD), heart rate (HR) recovery, and HR variability were measured.
Results: In the post-exercise recovery period, SBP dropped significantly in the BRJ-NO3rich group (-9.28mmHg [95%CI: -1.68 to -16.88] ES: -0.65, p=0.019) compared to placebo after acute ingestion. The FMD values increased after acute BRJ-NO3rich on post-exercise (3.18% [0.36 to 5.99] ES: 0.87, p=0.031). After the one-week intervention, FMD values were higher in the BRJ-NO3rich group before (4.5% [1.62 to 7.37] ES: 1.21, p=0.005) and post-exercise measurements (4.2% [1.52 to 6.87] ES: 1.22, p= 0.004) vs. placebo. HRV indices with remarkable parasympathetic modulation to heart recovered faster on the BRJ-NO3rich group than placebo group. No between-group differences were identified in values of HR post-exercise recovery in the 30s, 60s, 120s, 180s, and 300s.
Conclusions: Acute and short-term BRJ-NO3rich ingestion may enhance cardiovascular and autonomic behavior in response to aerobic exercise in postmenopausal women diagnosed with SAH.
