Sport, Health and Exercise Science Research Group, Department for Health, University of Bath, Bath, United Kingdom.
Med Sci Sports Exerc. 2012 Nov;44(11):2213-9. doi: 10.1249/MSS.0b013e3182640f48.
The objective of this study is to examine the effects of acute ingestion of dietary nitrate on endurance running performance in highly trained cross-country skiers. Dietary nitrate has been shown to reduce the oxygen cost of submaximal exercise and improve tolerance of high-intensity exercise, but it is not known if this holds true for highly trained endurance athletes.
Ten male junior cross-country skiers (V˙O(2max)) ≈ 70 mL·kg·min) each completed two trials in a randomized, double-blind design. Participants ingested potassium nitrate (614-mg nitrate) or a nitrate-free placebo 2.5 h before two 5-min submaximal tests on a treadmill at 10 km·h (≈55% of V˙O(2max)) and 14 km·h (≈75% of V˙O(2max)), followed by a 5-km running time trial on an indoor track.
Plasma nitrite concentrations were higher after nitrate supplementation (325 ± 95 nmol·L) compared with placebo (143 ± 59 nmol·L, P < 0.001). There was no significant difference in 5-km time-trial performance between nitrate (1005 ± 53 s) and placebo treatments (996 ± 49 s, P = 0.12). The oxygen cost of submaximal running was not significantly different between placebo and nitrate trials at 10 km·h (both 2.84 ± 0.34 L·min) and 14 km·h (3.89 ± 0.39 vs. 3.77 ± 0.62 L·min).
Acute ingestion of dietary nitrate may not represent an effective strategy for reducing the oxygen cost of submaximal exercise or for enhancing endurance exercise performance in highly trained cross-country skiers.
本研究旨在检验急性摄入饮食硝酸盐对训练有素的越野滑雪运动员耐力跑表现的影响。饮食硝酸盐已被证明可降低次最大运动的氧气成本并提高高强度运动的耐受性，但尚不清楚这是否适用于训练有素的耐力运动员。
10 名男性青少年越野滑雪运动员（V˙O(2max)）≈70 mL·kg·min））在随机、双盲设计中每人完成两项试验。参与者在 2.5 小时前摄入硝酸钾（614 毫克硝酸盐）或无硝酸盐安慰剂，然后在跑步机上进行两次 5 分钟的次最大测试，速度分别为 10 公里/小时（≈55%的 V˙O(2max)）和 14 公里/小时（≈75%的 V˙O(2max)），随后在室内赛道上进行 5 公里跑步计时赛。
与安慰剂相比，硝酸盐补充后血浆亚硝酸盐浓度更高（325 ± 95 nmol·L）与安慰剂（143 ± 59 nmol·L，P < 0.001）。硝酸盐（1005 ± 53 秒）和安慰剂治疗（996 ± 49 秒，P = 0.12）之间 5 公里计时赛表现无显著差异。在 10 公里/小时（均为 2.84 ± 0.34 L·min）和 14 公里/小时（3.89 ± 0.39 对 3.77 ± 0.62 L·min）时，亚最大跑步的氧气消耗在安慰剂和硝酸盐试验之间没有显著差异。
急性摄入饮食硝酸盐可能不是降低次最大运动氧气成本或提高训练有素的越野滑雪运动员耐力运动表现的有效策略。
