Resumen de A Single Dose of Beetroot Juice Enhances Cycling Performance in Simulated Altitude.
Philip E. James, Chris Easton, David J. Muggeridge, Christopher C.F. Howe, Owen Spendiff, Charles R. Pedlar
AB Introduction: Increasing nitric oxide bioavailability via supplementation with nitrate-rich beetroot juice (BR) has been shown to attenuate the negative effect of hypoxia on peripheral oxygen saturation and exercise tolerance. Purpose: We investigated the effects of a single dose of concentrated BR on the physiological responses to submaximal exercise and time trial (TT) performance in trained cyclists exposed to moderate simulated altitude (approximately 2500 m). Methods: Nine competitive amateur male cyclists (age, 28 +/- 8 yr; V[spacing dot above]O2peak at altitude, 51.9 +/- 5.8 mL[middle dot]kg-1[middle dot]min-1) completed four exercise trials consisting of an initial graded test to exhaustion and three performance trials on a cycle ergometer. The performance trials comprised 15 min of submaximal steady-state exercise at 60% maximum work rate and a 16.1-km TT. The second and third trials were preceded by ingestion of either 70 mL of BR or nitrate-depleted BR (PLA) 3 h before exercise. Results: Plasma nitrate (PLA, 39.1 +/- 3.5 [micro]M; BR, 150.5 +/- 9.3 [micro]M) and nitrite (PLA, 289.8 +/- 27.9 nM; BR, 678.1 +/- 103.5 nM) measured immediately before exercise were higher after ingestion of BR compared with that after PLA (P < 0.001, P = 0.004). V[spacing dot above]O2 during steady-state exercise was lower in the BR trial (2542 +/- 114 mL[middle dot]min-1) than that in the PLA trial (2727 +/- 85 mL[middle dot]min-1, P = 0.049). TT performance was significantly faster after BR (1664 +/- 14 s) than that after PLA (1702 +/- 15 s, P = 0.021). Conclusion: A single dose of BR lowered V[spacing dot above]O2 during submaximal exercise and enhanced TT performance of trained cyclists in normobaric hypoxia. Consequently, ingestion of BR may be a practical and effective ergogenic aid for endurance exercise at altitude
