The Effect of Isotonic Beetroot Supplementation on High-intensity Time-trial Performance

Ingested beetroot contains inorganic nitrate (NO3-) which is later converted to nitric oxide (NO) in the bloodstream. NO is an important signaling molecule with several physiological functions in the body including acting as a vasodilator, expanding arteries and improving blood flow. These functions mean that beetroot juice has become of strong interest in the field of exercise and is a recommended supplement for athletes to improve performance in recent consensus statements by the International Olympic Committee on dietary supplements. Importantly, the consumption of beetroot has been shown to improve skeletal muscle contractility and metabolism, hence, enhancing high-intensity exercise performance . Isotonic sports drinks contain carbohydrates and sodium, which also improve exercise performance by providing exogenous glucose for energy to the working muscle and central nervous system and enabling faster absorption of fluid into the bloodstream. The ingestion of exogenous nitrate and isotonic-carbohydrate drink are recognized strategies for promoting exercise performance but whether they can be effectively combined has not been shown. This study will compare the salivary nitrite response, muscle oxygenation and time-trial performance after ingestion of two drinks either high in nitrate or with no nitrate. Participants will ingest the two drinks in a randomised, crossover double-blind trial. One hour after drink ingestion they will undertake high intensity intermittent exercise for 30 minutes followed by a 10 km time trial on a cycle ergometer. Time trial will be compared between trials as the main outcome. It is hypothesised that the drink high in nitrate will lead to faster time trial completion.