Influence of beetroot juice supplementation on intermittent exercise performance

Lee J. Wylie, Stephen J. Bailey, James Kelly, James R. Blackwell, Anni Vanhatalo, Andrew M. Jones

This study tested the hypothesis that nitrate (NO3 (-)) supplementation would improve performance during high-intensity intermittent exercise featuring different work and recovery intervals. Ten male team-sport players completed high-intensity intermittent cycling tests during separate 5-day supplementation periods with NO3 (-)-rich beetroot juice (BR; 8.2 mmol NO3 (-) day(-1)) and NO3 (-)-depleted beetroot juice (PL; 0.08 mmol NO3 (-) day(-1)). Subjects completed: twenty-four 6-s all-out sprints interspersed with 24 s of recovery (24 × 6-s); seven 30-s all-out sprints interspersed with 240 s of recovery (7 × 30-s); and six 60-s self-paced maximal efforts interspersed with 60 s of recovery (6 × 60-s); on days 3, 4, and 5 of supplementation, respectively. Plasma [NO2 (-)] was 237 % greater in the BR trials. Mean power output was significantly greater with BR relative to PL in the 24 × 6-s protocol (568 ± 136 vs. 539 ± 136 W; P < 0.05), but not during the 7 × 30-s (558 ± 95 vs. 562 ± 94 W) or 6 × 60-s (374 ± 57 vs. 375 ± 59 W) protocols (P > 0.05). The increase in blood [lactate] across the 24 × 6-s and 7 × 30-s protocols was greater with BR (P < 0.05), but was not different in the 6 × 60-s protocol (P > 0.05). BR might be ergogenic during repeated bouts of short-duration maximal-intensity exercise interspersed with short recovery periods, but not necessarily during longer duration intervals or when a longer recovery duration is applied. These findings suggest that BR might have implications for performance enhancement during some types of intermittent exercise.