Human Exercise Physiology Research Laboratory, Department of Kinesiology, 1A Natatorium, Kansas State University, Manhattan, KS 66506-0302, USA.
Respir Physiol Neurobiol. 2011 Sep 15;178(2):261-8. doi: 10.1016/j.resp.2011.06.020. Epub 2011 Jun 29.
The accumulation of reactive oxygen species (ROS) is associated with muscular fatigue. The antioxidant N-acetylcysteine (NAC) can extend time to fatigue (TTF), but the effect appears to be exercise intensity dependent. The purpose of this study was to determine the effects of an acute oral dose of NAC on time to fatigue (TTF), critical power (CP), W' (curvature constant), V(O2) kinetics and muscle EMG during cycling exercise. Male (n=7) subjects performed four tests at power outputs corresponding to 80, 90, 100, and 110% of the peak power output achieved during the incremental test (Pmax) under NAC and placebo (PLA) conditions. TTF was increased only in the 80% Pmax trial (p=0.033). CP was higher with NAC (NAC: 232±28 W versus PLA: 226±31 W; p=0.032), but W' tended to decrease (NAC: 15.5±3.8 kJ versus W': 16.4±4.5 kJ; p=0.10). The change in W' was negatively related to the change in CP (r = -0.96). MdPF and RMS of EMG tended to change less with NAC. There were no significant differences in V(O2) kinetics. These results demonstrate that oral NAC was successful in extending time to fatigue at 80% Pmax but not at higher work rates.
活性氧（ROS）的积累与肌肉疲劳有关。抗氧化剂 N-乙酰半胱氨酸（NAC）可以延长疲劳时间（TTF），但这种效果似乎取决于运动强度。本研究的目的是确定急性口服 NAC 对自行车运动中疲劳时间（TTF）、临界功率（CP）、W'（曲率常数）、V（O2）动力学和肌肉 EMG 的影响。7 名男性受试者在 NAC 和安慰剂（PLA）条件下，以递增试验中达到的最大功率输出的 80%、90%、100%和 110%的功率输出进行了四项测试。只有在 80%Pmax 试验中 TTF 增加（p=0.033）。NAC 时 CP 更高（NAC：232±28 W 与 PLA：226±31 W；p=0.032），但 W' 有下降趋势（NAC：15.5±3.8 kJ 与 W'：16.4±4.5 kJ；p=0.10）。W'的变化与 CP 的变化呈负相关（r = -0.96）。MdPF 和 EMG 的 RMS 随着 NAC 的变化趋于减少。V（O2）动力学没有显著差异。这些结果表明，口服 NAC 成功地延长了 80%Pmax 时的疲劳时间，但在更高的工作率下没有效果。
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