Beetroot Juice Supplementation Does Not Improve Performance of Elite 1500-m Runners.

• Autores: Robert K. Boorsma, Lawrence L. Spriet, Jamie Whitfield
• Localización: Medicine & Science in Sports & exercise: Official Journal of the American College of Sports Medicine, ISSN 0195-9131, Vol. 46, Nº. 12, 2014, págs. 2326-2333
• Idioma: inglés
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• Resumen

  • AB Purpose: Dietary nitrate supplementation with beetroot juice (BR) has received widespread attention as an ergogenic aid. However, recent evidence in well-trained cyclists has not consistently reported improved cycling economy or performance. The present study examined the effects of acute and chronic BR supplementation on V[spacing dot above]O2 during submaximal running and 1500-m time trial (TT) performance of elite distance runners. Methods: Eight male 1500-m runners (V[spacing dot above]O2peak, 80 +/- 5 mL[middle dot]kg-1[middle dot]min-1; 1500-m personal best, 3:56 +/- 9 s) participated in this study. In a randomized, double-blind, crossover design, subjects supplemented with BR or a nitrate-free BR placebo (PL) for 8 d separated by at least 1 wk. On days 1 (acute) and 8 (chronic), subjects ingested 210 mL of BR (19.5-mmol nitrate) or PL and completed a submaximal treadmill run and 1500-m TT on an indoor 200-m track. Results: Plasma nitrate increased from 37 +/- 15 to 615 +/- 151 [mu]M (acute) and 870 +/- 259 [mu]M (chronic) after BR supplementation. There were no V[spacing dot above]O2 differences between conditions at 50%, 65%, and 80% V[spacing dot above]O2peak (acute PL, 4194 +/- 90 mL[middle dot]min-1; chronic PL, 4216 +/- 95 mL[middle dot]min-1; acute BR, 4192 +/- 113 mL[middle dot]min-1; chronic BR, 4299 +/- 92 mL[middle dot]min-1). The 1500-m TT was unaffected by acute or chronic BR supplementation (acute PL, 4:10.4 min:s +/- 2.5 s; chronic PL, 4:11.4 min:s +/- 2.7 s; acute BR, 4:10.7 min:s +/- 1.5 s; chronic BR, 4:10.5 min:s +/- 2.2 s). However, two subjects improved their TT performance after acute (5.8 and 5.0 s) and chronic BR supplementation (7.0 and 0.5 s). Conclusions: Acute and chronic BR supplementation did not reduce running V[spacing dot above]O2 or improve 1500-m TT performance of a group of elite distance runners, but two responders to BR were identified