Author(s): Hoon MW, Jones AM, Johnson NA, Blackwell JR, Broad EM,
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Abstract CONTEXT: Beetroot juice is a naturally rich source of inorganic nitrate (NO(3-)), a compound hypothesized to enhance endurance performance by improving exercise efficiency. PURPOSE: To investigate the effect of different doses of beetroot juice on 2000-m ergometer-rowing performance in highly trained athletes. METHODS: Ten highly trained male rowers volunteered to participate in a placebo-controlled, double-blinded crossover study. Two hours before undertaking a 2000-m rowing-ergometer test, subjects consumed beetroot juice containing 0 mmol (placebo), 4.2 mmol (SINGLE), or 8.4 mmol (DOUBLE) NO(3-). Blood samples were taken before supplement ingestion and immediately before the rowing test for analysis of plasma [NO(3-)] and [nitrite (NO(2-))]. RESULTS: The SINGLE dose demonstrated a trivial effect on time to complete 2000 m compared with placebo (mean difference: 0.2 ± 2.5 s). A possibly beneficial effect was found with DOUBLE compared with SINGLE (mean difference -1.8 ± 2.1 s) and with placebo (-1.6 ± 1.6 s). Plasma [NO(2-)] and [NO(3-)] demonstrated a dose-response effect, with greater amounts of ingested nitrate leading to substantially higher concentrations (DOUBLE > SINGLE > placebo). There was a moderate but insignificant correlation (r = -.593, P = .055) between change in plasma [NO(2-)] and performance time. CONCLUSION: Compared with nitratedepleted beetroot juice, a high (8.4 mmol NO(3-)) but not moderate (4.2 mmol NO(3-)) dose of NO(3-) in beetroot juice, consumed 2 h before exercise, may improve 2000-m rowing performance in highly trained athletes.
This article was published in Int J Sports Physiol Perform
and referenced in Journal of Nutrition Research