Nutrition, Physical Activity and Health Research Group, University of Stirling, Stirling, Scotland.
J Sports Sci. 2009 Oct;27(12):1261-9. doi: 10.1080/02640410903165077.
The aim of this study was to determine if inducing metabolic alkalosis would alter neuromuscular control after 50 min of standardized submaximal cycling. Eight trained male cyclists (mean age 32 years, s = 7; [Vdot]O(2max) 62 ml . kg(-1) x min(-1), s = 8) ingested capsules containing either CaCO(3) (placebo) or NaHCO(3) (0.3 g x kg(-1) body mass) in eight doses over 2 h on two separate occasions, commencing 3 h before exercise. Participants performed three maximal isometric voluntary contractions (MVC) of the knee extensors while determining the central activation ratio by superimposing electrical stimulation both pre-ingestion and post-exercise, followed by a 50-s sustained maximal contraction in which force, EMG amplitude, and muscle fibre conduction velocity were assessed. Plasma pH, blood base excess, and plasma HCO(3) were higher (P < 0.01) during the NaHCO(3) trial. After cycling, muscle fibre conduction velocity was higher (P < 0.05) during the 50-s sustained maximal contraction with NaHCO(3) than with placebo (5.1 m x s(-1), s = 0.4 vs. 4.2 m x s(-1), s = 0.4) while the EMG amplitude remained the same. Force decline rate was less (P < 0.05) during alkalosis-sustained maximal contraction and no differences were shown in central activation ratio. These data indicate that induced metabolic alkalosis can increase muscle fibre conduction velocity following prolonged submaximal cycling.
本研究旨在确定诱导代谢性碱中毒是否会改变 50 分钟标准化次最大强度自行车运动后的神经肌肉控制。8 名训练有素的男性自行车运动员（平均年龄 32 岁，标准差 7；最大摄氧量[Vdot]O(2max) 62 毫升. 公斤(-1) x 分钟(-1)，标准差 8）在两次不同的时间分别摄入含有 CaCO(3)（安慰剂）或 NaHCO(3)（0.3 g x 公斤(-1) 体重）的胶囊，分 8 次在 2 小时内服用，运动前 3 小时开始。参与者在摄入前和摄入后叠加电刺激，进行了三次最大等长自主收缩（MVC）的膝关节伸肌，同时确定中枢激活比，然后进行 50 秒的持续最大收缩，评估力、肌电图幅度和肌肉纤维传导速度。在 NaHCO(3)试验中，血浆 pH、血液碱剩余和血浆 HCO(3)更高（P < 0.01）。运动后，在 NaHCO(3)试验中，50 秒持续最大收缩时肌肉纤维传导速度更高（P < 0.05），而在安慰剂试验中为 5.1 m x s(-1)，标准差 0.4 比 4.2 m x s(-1)，标准差 0.4，而肌电图幅度保持不变。在酸中毒持续最大收缩时力下降率较低（P < 0.05），中枢激活比没有差异。这些数据表明，诱导的代谢性碱中毒可以增加长时间次最大强度自行车运动后的肌肉纤维传导速度。
