Repeated-sprint performance and plasma responses following beetroot juice supplementation do not differ between recreational, competitive and elite sprint athletes

European Journal of Sport Science
Q1
Feb 2018
Citations:48
Influential Citations:5
Interventional (Human) Studies
93
COI
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Methods
Randomized, double-blind, placebo-controlled cross-over design in 52 healthy sprint athletes who completed the protocol: elite sprinters (n=10; 5M/5F), competitive sprinters (n=22; 14M/8F), recreational athletes (n=20; 10M/10F). Age by group: Males—Recreational 27±6, Competitive 19±1, Elite 21±2; Females—Recreational 33±7, Competitive 20±3, Elite 22±3. Wingate sprint protocol (three 30-s sprints) with blood samples for plasma nitrate and nitrite; tests performed after ingestion of BR or PLA.
Intervention
Beetroot juice (nitrate-rich) 140 mL daily for 6 days (~800 mg nitrate per day); Beetroot juice (nitrate-depleted) 140 mL daily for 6 days (~0.5 mg nitrate per day); taken at breakfast.
Results
BR supplementation increased plasma nitrate and nitrite concentrations vs PLA across all sport levels (P<0.001) with no differences between sport levels. Peak power across Wingates did not differ between BR and PLA (1338±30 W vs 1333±30 W; P=0.62); mean power did not differ (P=0.86); no Wingate×treatment interaction (P=0.48). Time to peak power improved by ~2.8% with BR vs PLA (median difference −0.2 s; 95% CI −1.0 to 0.4; P=0.007), consistent across Wingates and sport levels. Conclusion: Plasma and sprint-performance responses to beetroot juice do not differ by sport level, but BR reduces time to reach peak power, potentially enhancing acceleration in high-intensity tasks for recreational and elite athletes.
Limitations
Not powered to detect sex differences within sport levels; athletes across sport levels tested in different time periods due to practical reasons; day-to-day performance variation; eight missing DEXA measurements (LLFFM/FFMI) across participants (4 male competitive, 3 female competitive, 1 male elite); one dropout; 6-day supplementation; Wingate tests conducted in lab settings, which may not fully reflect real-world performance.

Abstract

Abstract Purpose: There is an ongoing debate whether highly trained athletes are less responsive to the ergogenic properties of nitrate. We assessed the effects of nitrate supplementation on plasma nitrate and nitrite concentrations and repeated-spri...