Wilkerson, D. P., Hayward, G. M., Bailey, S. J., Vanhatalo, A., Blackwell, J. R., & Jones, A. M. (2012). Influence of acute dietary nitrate supplementation on 50 mile time-trial performance in well-trained cyclists. European Journal of Applied Physiology, 112. On line publication, April 23, 2012.

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Dietary nitrate supplementation has been reported to improve short distance time-trial performance by 13% in club-level cyclists. It is not known if these ergogenic effects persist in longer endurance events or if dietary nitrate supplementation can enhance performance to the same extent in better trained individuals.

Well-trained male cyclists (N = 8) performed two laboratory-based 50 mile time-trials: (1) 2.5 hours after consuming 0.5 liters of nitrate-rich beetroot juice and (2) 2.5 hours after consuming 0.5 liters of nitrate-depleted beetroot juice as a placebo. Beetroot juice significantly elevated plasma [NO2-] and marginally, but not significantly, reduced completion time for the 50 mile time-trial. There was a significant correlation between the increased post-beverage plasma [NO2-] with beetroot juice and the reduction in time-trial completion time. Power output (PO) was similar between the conditions but oxygen uptake (VO2) tended to be lower in the beetroot juice condition, resulting in a significantly greater PO/VO2 ratio when compared to the placebo.

Implication. Acute dietary supplementation with beetroot juice (nitrate) did not significantly improve 50 mile time-trial performance in well-trained cyclists. It is possible that the better training status of the cyclists in this study might reduce the physiological and performance response to nitrate supplementation compared with the moderately trained athletes tested in earlier studies.

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