Plain language summary
Beetroot juice supplementation has been shown to effectively increase blood nitric oxide (NO) concentrations, promoting vasodilation and increasing blood circulation. Several studies have found an ergogenic effect of beetroot juice supplementation in endurance training, which requires high oxidative energy, however only few have examined the efficacy of supplementation for high-intensity, short-duration exercise. The aim of this paper was to review experiments that specifically tested beetroot supplementation on high-intensity, intermittent exercise. Nine published articles indicated that beetroot juice did improve performance by diminishing muscular fatigue and recovering phosphocreatine reserves. Based on these results, the authors conclude that the current observations will need confirmation from larger studies in the future.
undefined: Beetroot juice contains high levels of inorganic nitrate (NO ) and its intake has proved effective at increasing blood nitric oxide (NO) concentrations. Given the effects of NO in promoting vasodilation and blood flow with beneficial impacts on muscle contraction, several studies have detected an ergogenic effect of beetroot juice supplementation on exercise efforts with high oxidative energy metabolism demands. However, only a scarce yet growing number of investigations have sought to assess the effects of this supplement on performance at high-intensity exercise. Here we review the few studies that have addressed this issue. The databases Dialnet, Elsevier, Medline, Pubmed and Web of Science were searched for articles in English, Portuguese and Spanish published from 2010 to March 31 to 2017 using the keywords: beet or beetroot or nitrate or nitrite and supplement or supplementation or nutrition or "sport nutrition" and exercise or sport or "physical activity" or effort or athlete. Nine articles fulfilling the inclusion criteria were identified. Results indicate that beetroot juice given as a single dose or over a few days may improve performance at intermittent, high-intensity efforts with short rest periods. The improvements observed were attributed to faster phosphocreatine resynthesis which could delay its depletion during repetitive exercise efforts. In addition, beetroot juice supplementation could improve muscle power output via a mechanism involving a faster muscle shortening velocity. The findings of some studies also suggested improved indicators of muscular fatigue, though the mechanism involved in this effect remains unclear.