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

in International Journal of Sports Physiology and Performance
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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.

Hoon and Johnson are with the Discipline of Exercise and Sports Science, University of Sydney, Lidcombe, NSW, Australia. Jones and Blackwell are with Sport and Health Sciences, University of Exeter, Exeter, UK. Broad, Lundy, and Burke are with Sports Nutrition, and Rice, Physiology, Australian Institute of Sport, Bruce, ACT, Australia. Address author correspondence to Matthew Hoon at matthew.hoon@sydney.edu.au.