Objective

The aim was to quantify the proportion of the literature on caffeine supplementation that reports habitual caffeine consumption, and determine the influence of habitual consumption on the acute exercise response to caffeine supplementation, using a systematic review and meta-analytic approach.

Methods

Three databases were searched, and articles screened according to inclusion/exclusion criteria. Three-level meta-analyses and meta-regression models were used to investigate the influence of habitual caffeine consumption on caffeine’s overall ergogenic effect and within different exercise types (endurance, power, strength), in men and women, and in trained and untrained individuals. Sub-analyses were performed according to the following: acute relative dose (< 3, 3–6, > 6 mg/kg body mass [BM]); whether the acute caffeine dose provided was lower or higher than the mean daily caffeine dose; and the caffeine withdrawal period prior to the intervention (< 24, 24–48, > 48 h).

Results

Sixty caffeine studies included sufficient information on habitual consumption to be included in the meta-analysis. A positive overall effect of caffeine was shown in comparison to placebo (standard mean difference [SMD] = 0.25, 95% confidence interval [CI] 0.20–0.30; p < 0.001) with no influence of relative habitual caffeine consumption (p = 0.59). Subgroup analyses showed a significant ergogenic effect when the caffeine dose was < 3 mg/kg BM (SMD = 0.26, 95% CI 0.12–0.40; p = 0.003) and 3–6 mg/kg BM (SMD = 0.26, 95% CI 0.21–0.32; p < 0.0001), but not > 6 mg/kg BM (SMD = 0.11, 95% CI − 0.07 to 0.30; p = 0.23); when the dose was both higher (SMD = 0.26, 95% CI 0.20–0.31; p < 0.001) and lower (SMD = 0.21, 95% CI 0.06–0.36; p = 0.006) than the habitual caffeine dose; and when withdrawal was < 24 h, 24–48 h, and > 48 h. Caffeine was effective for endurance, power, and strength exercise, with no influence (all p ≥ 0.23) of relative habitual caffeine consumption within exercise types. Habitual caffeine consumption did not modify the ergogenic effect of caffeine in male, female, trained or untrained individuals.

Conclusion

Habitual caffeine consumption does not appear to influence the acute ergogenic effect of caffeine.

中文翻译：

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我可以喝咖啡吗？确定习惯性咖啡因摄入是否影响咖啡因的增效作用的系统评价和荟萃分析

客观的

目的是量化关于咖啡因补充的文献中报告习惯性咖啡因摄入的比例，并使用系统评价和荟萃分析方法确定习惯性摄入对补充咖啡因的急性运动反应的影响。

方法

搜索了三个数据库，并根据纳入/排除标准筛选了文章。三级荟萃分析和荟萃回归模型用于研究习惯性咖啡因摄入对咖啡因的整体增效效果以及不同运动类型（耐力、力量、力量）、男性和女性以及受过训练和未受过训练的个体的影响. 根据以下进行子分析：急性相对剂量（< 3, 3-6, > 6 mg/kg 体重 [BM]）；提供的急性咖啡因剂量是否低于或高于平均每日咖啡因剂量；以及干预前的咖啡因戒断期（< 24, 24-48, > 48 h）。

结果

60 项咖啡因研究包括足够的关于习惯性消费的信息，以纳入荟萃分析。与安慰剂相比，咖啡因具有积极的总体效果（标准平均差 [S​​MD] = 0.25，95% 置信区间 [CI] 0.20–0.30；p  < 0.001），相对习惯性咖啡因摄入没有影响（p  = 0.59） . 亚组分析显示，当咖啡因剂量 < 3 mg/kg BM (SMD = 0.26, 95% CI 0.12–0.40; p  = 0.003) 和 3–6 mg/kg BM (SMD = 0.26, 95% CI 0.21–0.32；p  < 0.0001)，但不 > 6 mg/kg BM (SMD = 0.11, 95% CI - 0.07 to 0.30; p  = 0.23)；当剂量都较高时（SMD = 0.26, 95% CI 0.20–0.31；p < 0.001) 和低于习惯性咖啡因剂量 (SMD = 0.21, 95% CI 0.06–0.36; p = 0.006)；当戒断时间 < 24 小时、24-48 小时和 > 48 小时。咖啡因对耐力、力量和力量锻炼有效，对 运动类型中的相对习惯性咖啡因消耗没有影响（所有p ≥ 0.23）。习惯性摄入咖啡因不会改变咖啡因对男性、女性、受过训练或未受过训练的个体的增效作用。

结论

习惯性摄入咖啡因似乎不会影响咖啡因的急性增效作用。