Copenhagen Muscle Research Centre, Department of Exercise and Sport Sciences, University of Copenhagen, Denmark.
J Appl Physiol (1985). 2011 Nov;111(5):1372-9. doi: 10.1152/japplphysiol.01028.2010. Epub 2011 Aug 11.
The effect of oral caffeine ingestion on intense intermittent exercise performance and muscle interstitial ion concentrations was examined. The study consists of two studies (S1 and S2). In S1, 12 subjects completed the Yo-Yo intermittent recovery level 2 (Yo-Yo IR2) test with prior caffeine (6 mg/kg body wt; CAF) or placebo (PLA) intake. In S2, 6 subjects performed one low-intensity (20 W) and three intense (50 W) 3-min (separated by 5 min) one-legged knee-extension exercise bouts with (CAF) and without (CON) prior caffeine supplementation for determination of muscle interstitial K(+) and Na(+) with microdialysis. In S1 Yo-Yo IR2 performance was 16% better (P < 0.05) in CAF compared with PLA. In CAF, plasma K(+) at the end of the Yo-Yo IR2 test was 5.2 ± 0.1 mmol/l with no difference between the trials. Plasma free fatty acids (FFA) were higher (P < 0.05) in CAF than PLA at rest and remained higher (P < 0.05) during exercise. Peak blood glucose (8.0 ± 0.6 vs. 6.2 ± 0.4 mmol/l) and plasma NH(3) (137.2 ± 10.8 vs. 113.4 ± 13.3 μmol/l) were also higher (P < 0.05) in CAF compared with PLA. In S2 interstitial K(+) was 5.5 ± 0.3, 5.7 ± 0.3, 5.8 ± 0.5, and 5.5 ± 0.3 mmol/l at the end of the 20-W and three 50-W periods, respectively, in CAF, which were lower (P < 0.001) than in CON (7.0 ± 0.6, 7.5 ± 0.7, 7.5 ± 0.4, and 7.0 ± 0.6 mmol/l, respectively). No differences in interstitial Na(+) were observed between CAF and CON. In conclusion, caffeine intake enhances fatigue resistance and reduces muscle interstitial K(+) during intense intermittent exercise.
研究了口服咖啡因摄入对高强度间歇运动表现和肌肉间隙离子浓度的影响。该研究包括两项研究（S1 和 S2）。在 S1 中，12 名受试者在摄入咖啡因（6 毫克/千克体重；CAF）或安慰剂（PLA）之前完成了 Yo-Yo 间歇性恢复水平 2（Yo-Yo IR2）测试。在 S2 中，6 名受试者进行了一次低强度（20 W）和三次高强度（50 W）3 分钟（间隔 5 分钟）单腿伸膝运动，其中（CAF）和没有（CON）之前进行了咖啡因补充，以通过微透析测定肌肉间隙 K（+）和 Na（+）。在 S1 的 Yo-Yo IR2 测试中，CAF 组的表现比 PLA 组提高了 16%（P<0.05）。在 CAF 中，Yo-Yo IR2 测试结束时的血浆 K（+）为 5.2±0.1 mmol/L，两次试验之间没有差异。血浆游离脂肪酸（FFA）在 CAF 中高于 PLA（P<0.05），在运动过程中仍保持较高水平（P<0.05）。峰值血糖（8.0±0.6 对 6.2±0.4 mmol/L）和血浆 NH3（137.2±10.8 对 113.4±13.3 μmol/L）也高于 PLA（P<0.05）。在 S2 中，CAF 中 20-W 和三个 50-W 周期结束时的间隙 K（+）分别为 5.5±0.3、5.7±0.3、5.8±0.5 和 5.5±0.3 mmol/L，低于 CON（7.0±0.6、7.5±0.7、7.5±0.4 和 7.0±0.6 mmol/L，分别）（P<0.001）。CAF 和 CON 之间没有观察到间隙 Na（+）的差异。总之，咖啡因摄入可增强高强度间歇运动中的抗疲劳能力，并降低肌肉间隙 K（+）。
