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The Effect of Variable Doses of Inorganic Nitrate-Rich Beetroot Juice on Simulated 2000-m Rowing Performance in Trained Athletes

Matthew W. Hoon, Andrew M. Jones, Nathan A. Johnson, Jamie R. Blackwell, Elizabeth M. Broad, Bronwen Lundy, Anthony J. Rice, and Louise M. Burke

Context:

Beetroot juice is a naturally rich source of inorganic nitrate (NO3 ), 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) NO3 . Blood samples were taken before supplement ingestion and immediately before the rowing test for analysis of plasma [NO3 ] and [nitrite (NO2 )].

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 [NO2 ] and [NO3 ] 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 [NO2 ] and performance time.

Conclusion:

Compared with nitratedepleted beetroot juice, a high (8.4 mmol NO3 ) but not moderate (4.2 mmol NO3 ) dose of NO3 in beetroot juice, consumed 2 h before exercise, may improve 2000-m rowing performance in highly trained athletes.