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摘要
While the majority of studies reporting ergogenic effects of dietary nitrate have used a multiday supplementation protocol, some studies suggest that a single dose of dietary nitrate before exercise can also improve subsequent perfonuance. We aimed to compare the impact of acute and 6-day sodium nitrate supplementation on oxygen uptake (Vover dotO(2)) and time-trial performance in trained cyclists. Using a randomized, double-blind, cross-over design, 17 male cyclists (25 +/- 4 y, Vover dotO(2peak) 65 +/- 4 ml.kg(-1).min(-1), W-max 411 +/- 35 W) were subjected to 3 different trials; 5 days placebo and 1 day sodium nitrate supplementation (1-DAY); 6 days sodium nitrate supplementation (6-DAY); 6 days placebo supplementation (PLA). Nitrate was administered as 1097 mg sodium nitrate providing 800 mg (similar to 12.9 mmol) nitrate per day. Three hours after ingestion of the last supplemental bolus, indirect calorimetry was performed while subjects performed 30 min of exercise at 45% W-max and 30 min at 65% W-max on a cycle ergometer, followed by a 10 km time-trial. Immediately before exercise, plasma [nitrate] and [nitrite] increased to a similar extent during the 6-DAY and 1-DAY trial, but not with PLA (plasma nitrite: 501 +/- 205, 553 +/- 278, and 239 +/- 74 nM, respectively; p <.001). No differences were observed between interventions in Vover dotO(2) during submaximal exercise, or in time to complete the time-trial (6-DAY: 1004 (+/-) 61, 1-DAY: 1022 +/- 72, PLA: 1017 +/- 71 s; p =.28). We conclude that both acute and 6-days of sodium nitrate supplementation do not alter Vover dotO(2) during submaximal exercise or improve time-trial performance in highly trained cyclists, despite increasing plasma [nitrate] and [nitrite].
- 出版日期2017-2
