Pre-workout Nitrate Enhances Training-induced Benefits On Blood Pressure During And After Walking In Postmenopausal Women

Acute ingestion of nitrate rich beetroot juice (BRJ) demonstrates blood pressure lowering effects in younger adults; however, such benefits are often inconsistent among older adults. Prior work has yet to evaluate the effects of pre-workout BRJ combined with exercise training on blood pressure in postmenopausal women. PURPOSE: Determine whether pre-workout BRJ enhances training-induced benefits on blood pressure during and after submaximal walking compared to exercise training without BRJ (EX). METHODS: A two-arm design was used to compare 24 postmenopausal (65 ± 5 y; body mass index = 30.9 ± 3.6 kg/m2) women before and after 8 weeks of supervised multimodal exercise training. Group randomization to BRJ + EX (n = 12) or EX (n = 12) occurred following baseline assessments. BRJ (140 mL, Beet It®) was consumed for 7 weeks, ~2.5-3 h prior to each training session then discontinued during the last week to mitigate carry-over effects. Blood pressure was measured at rest, during treadmill walking, and 3-min into recovery. Isokinetic dynamometry was used to measure maximal knee extensor power (Pmax). Training-induced changes (Δ) were evaluated with two x two ANOVA. Effect sizes were used as a measure of substantive differences. Bivariate correlations were performed on relationships of interest. Data are reported as means ± SD. RESULTS: Between-group differences were not detected at baseline or post-intervention for resting blood pressure. However, during walking, a significant time by group interaction was observed wherein diastolic (-10 ± 7 mm Hg vs. + 3 ± 10 mm Hg; p = 0.002, g = 1.5) and mean arterial blood pressure were (-8 ± 7 mm Hg vs. 0 ± 7 mm Hg, p = 0.027, g = 1.0) significantly lower in BRJ + EX participants. Such differences persisted into the recovery period. Though BRJ + EX participants tended to exhibit a more robust improvement in Pmax, statistical significance was not reached (p = 0.070, d = 0.83). Interestingly, among all participants, ΔPmax was inversely correlated with Δdiastolic (r = -0.57, p = 0.014) and Δmean arterial blood pressure (r = -0.52, p = 0.025). CONCLUSIONS: Pre-workout BRJ combined with exercise training appears to improve blood pressure during and after submaximal walking in postmenopausal women. Contributing sources may be linked to knee extensor contractile function. Further research is warranted. Supported by the Indiana Clinical and Translational Sciences Institute funded in part by grant number UL1TR002529 from the NIH-NCATS