Recently, it seems that many athletes and exercise enthusiasts are turning to a reddish-purple colored fluid to boost performance – but is there evidence supporting beetroot juice as an ergogenic aid? A new study published in the American Journal of Physiology–Regulatory, Integrative and Comparative Physiology looked at the effects of chronic beetroot juice supplementation on circulatory dynamics during exercise. It is well known that beetroot juice is rich in nitrate which can promote vasodilation and increase blood flow to working tissues. Acute treatment with beetroot juice has been shown to lower systolic blood pressure and myocardial (heart muscle) oxygen demands during submaximal exercise, but the effects of chronic supplementation on cardiac output and peripheral resistance have not been conclusively confirmed.
Therefore, in the current study, the investigators compared the effects of 15 days of both beetroot juice and nitrate-depleted beetroot juice supplementation on plasma nitrate concentrations, blood pressure, cardiac output, total peripheral resistance, and rate pressure product (measure of myocardial oxygen demand) at rest and during progressive cycling exercise using 14 young male subjects. The research team found the natural beetroot juice (nitrate included) reduced the subjects’ blood pressure and total peripheral resistance at rest as well as during exercise. In addition, rate pressure product was decreased during exercise, while cardiac output was increased - but only at rest and when using a 30% workload. The cardiac and performance benefits where not found in subjects who consumed nitrate-depleted beetroot juice over the trial period.
The investigators summarized their conclusions as follows: