Division of Physical Therapy, Georgia State University, Atlanta, GA 30302-4019, USA.
Med Sci Sports Exerc. 2010 Jul;42(7):1375-87. doi: 10.1249/MSS.0b013e3181cabbd8.
Our objective was to perform a systematic review and meta-analysis of the research literature assessing the effect of caffeine ingestion on maximal voluntary contraction (MVC) strength and muscular endurance.
Thirty-four relevant studies between 1939 and 2008 were included in the meta-analyses of caffeine's effects on MVC strength (n = 27 studies) and muscular endurance (n = 23 studies). Effect sizes (ES) were calculated as the standardized mean difference and meta-analyses were completed using a random-effects model.
Overall, caffeine ingestion was found to result in a small beneficial effect on MVC strength (overall ES = 0.19, P = 0.0003). However, caffeine appears to improve MVC strength primarily in the knee extensors (i.e., by approximately 7%, ES = 0.37) and not in other muscle groups such as the forearm or the knee flexors. In an attempt to offer a physiological mechanism behind caffeine's ability to improve MVC strength, a meta-analysis was run on ES from nine studies that measured percent muscle activation during MVC in trials comparing caffeine versus placebo; the overall ES (0.67) was highly significant (P = 0.00008) and of moderate to large size, thus implicating an effect of caffeine on the CNS. Caffeine ingestion was also found to exert a small beneficial effect on muscular endurance (overall ES = 0.28, P = 0.00005). However, it appears caffeine improves muscular endurance only when it is assessed using open (i.e., by approximately 18%, ES = 0.37) and not fixed end point tests.
Overall, caffeine ingestion improves MVC strength and muscular endurance. The effect on strength appears exclusively in the knee extensors, and the effect on muscular endurance appears only detectable with open end point tests.
我们的目的是系统地回顾和分析评估咖啡因摄入对最大自主收缩（MVC）力量和肌肉耐力的影响的研究文献。
在对咖啡因对 MVC 力量（n = 27 项研究）和肌肉耐力（n = 23 项研究）的影响进行的荟萃分析中，纳入了 1939 年至 2008 年间的 34 项相关研究。效应量（ES）计算为标准化均数差，荟萃分析采用随机效应模型完成。
总体而言，咖啡因摄入对 MVC 力量有较小的有益影响（总体 ES = 0.19，P = 0.0003）。然而，咖啡因似乎主要改善膝关节伸肌的 MVC 力量（即约 7%，ES = 0.37），而不是其他肌肉群，如前臂或膝关节屈肌。为了提供咖啡因提高 MVC 力量的生理机制背后的机制，对比较咖啡因与安慰剂的九项研究中测量 MVC 期间肌肉激活百分比的 ES 进行了荟萃分析；总体 ES（0.67）非常显著（P = 0.00008），且为中等至较大，因此暗示咖啡因对中枢神经系统有影响。咖啡因摄入也对肌肉耐力产生较小的有益影响（总体 ES = 0.28，P = 0.00005）。然而，当使用开放式（即约 18%，ES = 0.37）而不是固定终点测试评估时，似乎咖啡因可以改善肌肉耐力。
总体而言，咖啡因摄入可提高 MVC 力量和肌肉耐力。对力量的影响仅出现在膝关节伸肌中，对肌肉耐力的影响仅在开放式终点测试中可检测到。
