Background: Post-menopausal women are at high risk of impaired cardiometabolic health due to age and inactivity-related declines in cardiorespiratory fitness, excess abdominal adiposity, and reduced oestrogen concentrations which contribute to vascular aging and endothelial dysfunction [1]. Despite low uptake, regular engagement in aerobic exercise is most effective at mitigating low cardiorespiratory fitness, cardiometabolic associated co-morbidity, and premature mortality. Previous studies also suggest inorganic nitrate (NO₃^–) supplementation can enhance cardiorespiratory fitness, both in post-menopausal women [2] and those with obesity [3], and may attenuate effort and pain perception during exercise [4], indicating its potential as an adjunctive therapy to support exercise involvement and potentiate improvements in cardiometabolic health. However, this remains relatively unexplored. Aim: To assess whether supplementing a short-term (3-wk) aerobic exercise training programme with NO₃^––rich beetroot juice accelerates improvements in cardiorespiratory fitness and parameters of cardiometabolic health and inflammation. Methods: 12 inactive, self-identified post-menopausal women (BMI>25kg/m²) completed 9 moderate-intensity (65% VO₂peak) exercise sessions on a cycle ergometer, which progressively increased in duration (30–60 minutes), either with (Ex+BRJ; n=7) or without (Ex; n=5) daily consumption of a NO₃^––rich beetroot juice shot (8.2 mmol/d; Beet it Sport Shot, James White Drinks ltd, United) in a single-blinded, parallel manner. At baseline and immediately following the protocol, anthropometrics, body composition (BIA), and resting systolic and diastolic BP (sphygmomanometer) were assessed and a submaximal exercise test completed to extrapolate maximal oxygen consumption (VO₂peak), the gold standard indicator of cardiorespiratory fitness [5]. Fasted blood samples were collected to assess cardiometabolic (glucose, insulin, HOMA-IR, TAG, HDL-C, LDL-C, TC:HDL) and inflammatory markers (IL-6, TNF-α). Paired and independent samples t-tests (two-tailed) were used to detect significant changes (α level p<0.05) within (pre-post intervention) and between groups, respectively. Where data was not normally distributed, Wilcoxon Signed Rank and Mann-Whitney U tests were employed. Data presented as mean ± SD. Results: VO₂peak increased 7.0% ± 3.8% (+1.7 ± 0.9 mL. kg.min^-1, p=0.002) in Ex+BRJ but remained unchanged in Ex (+0.6 ± 2.1 mL. kg.min^-1, p=0.534), however, no between-group differences were observed (p=0.248). Resting systolic BP reduced in Ex+BRJ (–9.8 ± 2.8mmHg, p<0.001) and Ex (–6.6 ± 2.5mmHg, p=0.004), with the decline tending to be greater in Ex+BRJ (–3.2mmHg, p=0.064). A minor reduction in body fat (–0.8 ± 0.8%, p=0.040) and fasting plasma IL-6 (–0.45 ± 0.14pg.mL^-1, p=0.049) was seen in Ex+BRJ, but not in Ex (both p>0.05). No other changes in body composition, RPE, blood lipids, glucose metabolism, or inflammatory markers were observed. Conclusions: Preliminary data suggests supplementation with NO₃^–-rich beetroot juice may potentiate improvements in cardiorespiratory fitness and certain indices of cardiometabolic health seen with short-term aerobic exercise alone. Further, larger-scale studies, with greater statistical power are needed to consolidate our findings and determine the potential of NO₃^–-rich beetroot juice as an exercise therapeutic in post-menopausal women with overweight or obesity.

The study protocol complied with the Declaration of Helsinki, with ethical approval granted by The MVLS Ethics Committee at The University of Glasgow.