Acute beetroot supplementation may improve blood pressure but not exercise economy in female masters swimmers

Abstract

It is known that beetroot supplements may improve exercise economy and blood pressure, but this has mainly been studied in males. Given that older female athletes are underrepresented in the literature, we aimed to determine if acute beetroot supplementation (BRS) improves exercise economy and blood pressure in masters female athletes (swimmers) during a treadmill exercise test. Methods: 11 participants (57.8±10.5 y) underwent 2 randomized, double-blinded trials, ingesting beetroot (BE) or placebo (PL). Salivary NO2- (sNO2-) and blood pressure (BP) were measured pre-ingestion (Base), pre-exercise (Pre), and 5 min post-exercise (Post). Oxygen consumption (VO2) was measured during the modified Balke test until HR reached 85% of age-predicted maximum. Exercise economy (ExEc) was defined as the average relative VO2 during min 3-4.5 of the test. sNO2- was determined using NO2- detection strips. Results: sNO2- increased from Base to Post in BE vs PL (32.5±7.0 vs 2.7±3.9% change, p=0.001). No treatment differences existed for ExEc (BE: 15.51±0.47 vs PL: 15.71±0.53 ml·kg-1·min-1, p=0.48). Diastolic BP was significantly lower in BE vs PL (Base: 74.6±1.7 vs 73.2±2.3, Pre: 73.6±1.8 vs 74.5±2.1, Post: 74.5±1.7 vs 76.1±2.2 mmHg, p=0.03, treatment by time). Conclusion: Acute BRS lowered diastolic BP, but did not improve exercise economy in these trained, normotensive athletes. Further research is warranted in menopausal and post-menopausal females, including those who are hypertensive, and in other female masters athlete groups.