Dietary nitrate supplementation enhances muscle contractile efficiency during knee-extensor exercise in humans

作者：Bailey Stephen J; Fulford Jonathan; Vanhatalo Anni; Winyard Paul G; Blackwell Jamie R; DiMenna Fred J; Wilkerson Daryl P; Benjamin Nigel; Jones Andrew M^*

来源：Journal of Applied Physiology, 2010, 109(1): 135-148.

DOI：10.1152/japplphysiol.00046.2010

• bioenergetics
• muscle metabolism
• (31)P-MRS
• fatigue
• efficiency
• respiratory control

Bailey SJ, Fulford J, Vanhatalo A, Winyard PG, Blackwell JR, DiMenna FJ, Wilkerson DP, Benjamin N, Jones AM. Dietary nitrate supplementation enhances muscle contractile efficiency during knee-extensor exercise in humans. J Appl Physiol 109: 135-148, 2010. First published May 13, 2010; doi:10.1152/japplphysiol.00046.2010.-The purpose of this study was to elucidate the mechanistic bases for the reported reduction in the O(2) cost of exercise following short-term dietary nitrate (NO(3)(-)) supplementation. In a randomized, double-blind, crossover study, seven men (aged 19-38 yr) consumed 500 ml/day of either nitrate-rich beetroot juice (BR, 5.1 mmol of NO(3)(-)/day) or placebo (PL, with negligible nitrate content) for 6 consecutive days, and completed a series of low-intensity and high-intensity "step" exercise tests on the last 3 days for the determination of the muscle metabolic (using (31)P-MRS) and pulmonary oxygen uptake ((V) over dotO(2)) responses to exercise. On days 4-6, BR resulted in a significant increase in plasma [ nitrite] (mean +/- SE, PL 231 +/- 76 vs. BR 547 +/- 55 nM; P < 0.05). During low-intensity exercise, BR attenuated the reduction in muscle phosphocreatine concentration ([PCr]; PL 8.1 +/- 1.2 vs. BR 5.2 +/- 0.8 mM; P < 0.05) and the increase in (V) over dotO(2) (PL 484 +/- 41 vs. BR 362 +/- 30 ml/min; P < 0.05). During high-intensity exercise, BR reduced the amplitudes of the [ PCr] (PL 3.9 +/- 1.1 vs. BR 1.6 +/- 0.7 mM; P < 0.05) and (V) over dotO(2) (PL 209 +/- 30 vs. BR 100 +/- 26 ml/min; P < 0.05) slow components and improved time to exhaustion (PL 586 +/- 80 vs. BR 734 +/- 109 s; P < 0.01). The total ATP turnover rate was estimated to be less for both low-intensity (PL 296 +/- 58 vs. BR 192 +/- 38 mu M/s; P < 0.05) and high-intensity (PL 607 +/- 65 vs. BR 436 +/- 43 mu M/s; P < 0.05) exercise. Thus the reduced O(2) cost of exercise following dietary NO(3)(-) supplementation appears to be due to a reduced ATP cost of muscle force production. The reduced muscle metabolic perturbation with NO(3)(-) supplementation allowed high-intensity exercise to be tolerated for a greater period of time.

• 出版日期2010-7