No improvement in endurance performance after a single dose of beetroot juice.

INTRODUCTION: Dietary nitrate supplementation has received much attention in the literature due to its proposed ergogenic properties. Recently, the ingestion of a single bolus of nitrate-rich beetroot juice (500 mL; ~6.2 mmol NO3-) was reported to improve subsequent time trial performance. However, this large volume of ingested beetroot juice does not represent a realistic dietary strategy for athletes to follow in a practical, performance-based setting. Therefore, we investigated the impact of ingesting a single bolus of concentrated nitrate-rich beetroot juice (140 mL; ~8.7 mmol NO3-) on subsequent 1 h time trial performance in well-trained cyclists. METHODS: Using a double-blind, repeated-measures crossover design (1 wk washout period), 20 trained male cyclists (26+/-1 y; O2peak=60+/-1 mL.kg-1.min-1; Wmax=398+/-7.7 W) ingested 140 mL of concentrated beetroot juice (8.7 mmol NO3-; BEET) or a placebo (nitrate-depleted beetroot juice; PLAC) with breakfast 2.5 h prior to an ~1 h cycling time trial (1073+/-21 kJ). Resting blood samples were collected every 30 min following BEET or PLAC ingestion and immediately post the time trial. RESULTS: Plasma nitrite concentration was higher in BEET vs PLAC prior to the onset of the time trial (532+/-32 vs 271+/-13 nM; P<0.001) but subsequent time trial performance (65.5+/-1.1 vs 65+/-1.1 s), power output (275+/-7 vs 278+/-7 W) and heart rate (170+/-2 vs 170+/-2 bpm), did not differ between BEET and PLAC treatments respectively (all P>0.05). CONCLUSION: Ingestion of a single bolus of concentrated (140 mL) beetroot juice (8.7 mmol NO3-) does not improve subsequent 1 h time trial performance in well-trained cyclists.