Effects of Nitrate on the Power-Duration Relationship for Severe-Intensity Exercise.
- Autores: James H. Kelly, Andrew M. Jones, Anni Vanhatalo, Daryl P. Wilkerson, Lee J. Wylie
- Localización: Medicine & Science in Sports & exercise: Official Journal of the American College of Sports Medicine, ISSN 0195-9131, Vol. 45, Nº. 9, 2013, págs. 1798-1806
- Idioma: inglés
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Resumen
AB Purpose: The power asymptote (critical power [CP]) and curvature constant (W') of the power-duration relationship dictate the tolerance to severe-intensity exercise. We tested the hypothesis that dietary nitrate supplementation would increase the CP and/or the W' during cycling exercise. Methods: In a double-blind, randomized, crossover study, nine recreationally active male subjects supplemented their diet with either nitrate-rich concentrated beetroot juice (BR; 2 x 250 mL[middle dot]d-1, ~8.2 mmol[middle dot]d-1 nitrate) or a nitrate-depleted BR placebo (PL; 2 x 250 mL[middle dot]d-1, ~0.006 mmol[middle dot]d-1 nitrate). In each condition, the subjects completed four separate severe-intensity exercise bouts to exhaustion at 60% of the difference between the gas exchange threshold and the peak power attained during incremental exercise (60% [DELTA]), 70% [DELTA], 80% [DELTA], and 100% peak power, and the results were used to establish CP and W'. Results: Nitrate supplementation improved exercise tolerance during exercise at 60% [DELTA] (BR, 696 +/- 120 vs PL, 593 +/- 68 s; P < 0.05), 70% [DELTA] (BR, 452 +/- 106 vs PL, 390 +/- 86 s; P < 0.05), and 80% [DELTA] (BR, 294 +/- 50 vs PL, 263 +/- 50 s; P < 0.05) but not 100% peak power (BR, 182 +/- 37 vs PL, 166 +/- 26 s; P = 0.10). Neither CP (BR, 221 +/- 27 vs PL, 218 +/- 26 W) nor W' (BR, 19.3 +/- 4.6 vs PL, 17.8 +/- 3 kJ) were significantly altered by BR. Conclusion: Dietary nitrate supplementation improved endurance during severe-intensity exercise in recreationally active subjects without significantly increasing either the CP or the W'.
