תזונה ותוספים Acute Dietary Nitrate Supplementation Improves Cycling Time Trial Performance.

[Mike Bikov]

Med Sci Sports Exerc. 2011 Apr 5. [Epub ahead of print]
Acute Dietary Nitrate Supplementation Improves Cycling Time Trial Performance.

Lansley KE, Winyard PG, Bailey SJ, Vanhatalo A, Wilkerson DP, Blackwell JR, Gilchrist M, Benjamin N, Jones AM.

1 Sport and Health Sciences, College of Life and Environmental Sciences, and 2 Peninsula College of Medicine and Dentistry, St. Luke's Campus, University of Exeter, Heavitree Road, Exeter, EX1 2LU, UK.
Abstract

PURPOSE: Dietary nitrate supplementation has been shown to reduce the O2 cost of sub-maximal exercise and to improve high-intensity exercise tolerance. However, it is presently unknown whether it may enhance performance during simulated competition. The present study investigated the effects of acute dietary nitrate supplementation on power output (PO), V˙o2, and performance during 4 km and 16.1 km cycling time trials (TT).

METHODS: Following familiarization, nine club-level competitive male cyclists were assigned in a randomized, cross-over design to consume 0.5 L of beetroot juice (BR; containing ~6.2 mmol of nitrate) or 0.5 L of nitrate-depleted beetroot juice (placebo, PL; containing ~0.0047 mmol of nitrate), ~2.5 h prior to the completion of a 4 km and a 16.1 km TT.

RESULTS: BR supplementation elevated plasma [nitrite] (PL: 241 ± 125 vs. BR: 575 ± 199 nM; P<0.05). The V˙o2 values during the TTs were not significantly different between the BR and PL conditions at any elapsed distance (P>0.05) but BR significantly increased mean PO during the 4 km (PL: 279 ± 51 vs. BR: 292 ± 44 W; P<0.05) and 16.1 km TT (PL: 233 ± 43 vs. BR: 247 ± 44 W; P<0.01). Consequently, BR improved 4 km performance by 2.8% (PL: 6.45 ± 0.42 vs. BR: 6.27 ± 0.35 min; P<0.05) and 16.1 km performance by 2.7% (PL: 27.7 ± 2.1 vs. BR: 26.9 ± 1.8 min; P<0.01).

CONCLUSION: These results suggest that acute dietary nitrate supplementation with 0.5 L BR improves cycling economy, as demonstrated by a higher PO for the same V˙o2, and enhances both 4 km and 16.1 km cycling TT performance.

PMID: 21471821 [PubMed - as supplied by publisher]

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