No improvement in endurance performance after a single dose of beetroot juice.
BACKGROUND
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-hr 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 yr, VO(2peak) 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 hr before an ~1-hr cycling time trial (1,073 ± 21 kJ). Resting blood samples were collected every 30 min after BEET or PLAC ingestion and immediately after the time trial.


RESULTS
Plasma nitrite concentration was higher in BEET than PLAC before the onset of the time trial (532 ± 32 vs. 271 ± 13 nM, respectively; p < .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 beats/min) did not differ between BEET and PLAC treatments (all p > .05).


CONCLUSIONS
Ingestion of a single bolus of concentrated (140 ml) beetroot juice (8.7 mmol NO3-) does not improve subsequent 1-hr time-trial performance in well-trained cyclists.
NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Centre+, Maastricht, The Netherlands.
Naomi M
NM
Cermak
Peter
P
Res
Rudi
R
Stinkens
Jon O
JO
Lundberg
Martin J
MJ
Gibala
Luc J C
LJ
van Loon
D000328:Adult; D056352:Athletes; D054874:Athletic Performance; D027461:Beta vulgaris / Q000737:chemistry*; D001642:Bicycling; D062408:Breakfast; D018592:Cross-Over Studies; D004311:Double-Blind Method; D005511:Food Handling; D000067030:Fruit and Vegetable Juices / Q000032:analysis; D006801:Humans; D008297:Male; D009566:Nitrates / Q000008:administration & dosage / Q000032:analysis; D009573:Nitrites / Q000097:blood; D009994:Osmolar Concentration; D058573:Performance-Enhancing Substances / Q000008:administration & dosage / Q000032:analysis; D010807:Physical Endurance; D018517:Plant Roots / Q000737:chemistry*; D064133:Sports Nutritional Physiological Phenomena; D055815:Young Adult
D009566:Nitrates; D009573:Nitrites; D058573:Performance-Enhancing Substances