Department of Nutrition, Exercise and Sports, Section of Integrated Physiology, University of Copenhagen, Copenhagen, Denmark.
Am J Physiol Regul Integr Comp Physiol. 2013 Aug 1;305(3):R313-21. doi: 10.1152/ajpregu.00048.2013. Epub 2013 May 29.
The present study examined whether a marked reduction in oxygen delivery, unlike findings in moderate-intensity exercise, would slow leg oxygen uptake (Vo2) kinetics during intense exercise (86 ± 3% of incremental test peak power). Seven healthy males (26 ± 1 years, means ± SE) performed one-legged knee-extensor exercise (60 ± 3 W) for 4 min in a control setting (CON) and with arterial infusion of N(G)-monomethyl-l-arginine and indomethacin in the working leg to reduce blood flow by inhibiting formation of nitric oxide and prostanoids (double blockade; DB). In DB leg blood flow (LBF) and oxygen delivery during the first minute of exercise were 25-50% lower (P < 0.01) compared with CON (LBF after 10 s: 1.1 ± 0.2 vs. 2.5 ± 0.3 l/min and 45 s: 2.7 ± 0.2 vs. 3.8 ± 0.4 l/min) and 15% lower (P < 0.05) after 2 min of exercise. Leg Vo2 in DB was attenuated (P < 0.05) during the first 2 min of exercise (10 s: 161 ± 26 vs. 288 ± 34 ml/min and 45 s: 459 ± 48 vs. 566 ± 81 ml/min) despite a higher (P < 0.01) oxygen extraction in DB. Net leg lactate release was the same in DB and CON. The present study shows that a marked reduction in oxygen delivery can limit the rise in Vo2 during the initial part of intense exercise. This is in contrast to previous observations during moderate-intensity exercise using the same DB procedure, which suggests that fast-twitch muscle fibers are more sensitive to a reduction in oxygen delivery than slow-twitch fibers.
本研究旨在探究在高强度运动（86 ± 3%递增测试最大功率）中，与中等强度运动的发现不同，供氧显著减少是否会减缓腿部氧摄取（Vo2）动力学。7 名健康男性（26 ± 1 岁，平均值 ± SE）在对照条件（CON）下和工作腿中给予 N(G)-单甲基-l-精氨酸和吲哚美辛的动脉输注，以通过抑制一氧化氮和前列腺素的形成来减少血流（双重阻断；DB），从而进行单腿伸膝运动（60 ± 3 W）4 分钟。在 DB 腿部运动中，血流（LBF）和运动 1 分钟时的供氧比 CON 低 25-50%（P < 0.01）（10 秒后 LBF：1.1 ± 0.2 与 2.5 ± 0.3 l/min 和 45 秒后：2.7 ± 0.2 与 3.8 ± 0.4 l/min），运动 2 分钟后低 15%（P < 0.05）。DB 腿部 Vo2 在运动的前 2 分钟内被抑制（P < 0.05）（10 秒：161 ± 26 与 288 ± 34 ml/min 和 45 秒：459 ± 48 与 566 ± 81 ml/min），尽管 DB 中的氧提取率更高（P < 0.01）。DB 和 CON 中的净腿部乳酸释放相同。本研究表明，供氧的显著减少可以限制高强度运动初始部分的 Vo2 增加。这与使用相同的 DB 程序在中等强度运动中观察到的情况形成对比，这表明快肌纤维比慢肌纤维对供氧减少更为敏感。
