Shannon Oliver Michael, Barlow Matthew John, Duckworth Lauren, Williams Emily, Wort Georgina, Woods David, Siervo Mario, O'Hara John Paul
Research Institute for Sport, Physical Activity, and Leisure, Leeds Beckett University, Leeds, LS163QS, UK.
Defence Medical Services, Royal Centre for Defence Medicine, Birmingham, B152TH, UK.
Eur J Appl Physiol. 2017 Apr;117(4):775-785. doi: 10.1007/s00421-017-3580-6. Epub 2017 Mar 1.
This study evaluated the effects of dietary nitrate (NO) supplementation on physiological functioning and exercise performance in trained runners/triathletes conducting short and longer-distance treadmill running time-trials (TT).
Eight trained male runners or triathletes completed four exercise performance tests comprising a 10 min warm up followed by either a 1500 or 10,000 m treadmill TT. Exercise performance tests were preceded 3 h before the exercise by supplementation with either 140 ml concentrated nitrate-rich (12.5 mmol nitrate) (BRJ) or nitrate-deplete (0.01 mmol nitrate) (PLA) beetroot juice.
BRJ supplementation significantly elevated plasma [NO] (P < 0.05). Resting blood pressure and exercise [Formula: see text] were not significantly different between BRJ and PLA (P > 0.05). However, post-exercise blood [lactate] was significantly greater in BRJ following the 1500 m TT (6.6 ± 1.2 vs. 6.1 ± 1.5 mM; P < 0.05), but not significantly different between conditions in the 10,000 m TT (P > 0.05). Performance in the 1500 m TT was significantly faster in BRJ vs. PLA (319.6 ± 36.2 vs. 325.7 ± 38.8 s; P < 0.05). Conversely, there was no significant difference in 10,000 m TT performance between conditions (2643.1 ± 324. 1 vs. 2649.9 ± 319.8 s, P > 0.05).
Acute BRJ supplementation significantly enhanced 1500 m, but not 10,000 m TT performance. These findings suggest that BRJ might be ergogenic during shorter distance TTs which allow for a high work rate, but not during longer distance TTs, completed at a lower work rate.
本研究评估了补充膳食硝酸盐（NO）对进行短距离和长距离跑步机计时赛（TT）的训练有素的跑步者/铁人三项运动员的生理功能和运动表现的影响。
八名训练有素的男性跑步者或铁人三项运动员完成了四项运动表现测试，包括10分钟的热身，然后进行1500米或10000米的跑步机计时赛。在运动前3小时，通过补充140毫升浓缩的富含硝酸盐（约12.5毫摩尔硝酸盐）（BRJ）或硝酸盐耗尽（约0.01毫摩尔硝酸盐）（PLA）的甜菜根汁来进行运动表现测试。
补充BRJ显著提高了血浆[NO]（P < 0.05）。BRJ和PLA之间的静息血压和运动[公式：见正文]没有显著差异（P > 0.05）。然而，在1500米计时赛后，BRJ组的运动后血[乳酸]显著更高（6.6±1.2对6.1±1.5毫摩尔；P < 0.05），但在10000米计时赛中各条件之间没有显著差异（P > 0.05）。与PLA相比，BRJ在1500米计时赛中的表现显著更快（319.6±36.2对325.7±38.8秒；P < 0.05）。相反，各条件之间在10000米计时赛表现上没有显著差异（2643.1±324.1对2649.9±319.8秒，P > 0.05）。
急性补充BRJ显著提高了1500米计时赛的成绩，但没有提高10000米计时赛的成绩。这些发现表明，BRJ在允许高工作率的较短距离计时赛中可能具有促力作用，但在以较低工作率完成的较长距离计时赛中则不然。
