Coventry University.
Int J Sport Nutr Exerc Metab. 2021 Jan 1;31(1):13-20. doi: 10.1123/ijsnem.2020-0204. Epub 2020 Dec 1.
There is growing evidence that caffeine and coffee ingestion prior to exercise provide similar ergogenic benefits. However, there has been a long-standing paradigm that habitual caffeine intake may influence the ergogenicity of caffeine supplementation. The aim of the present study was to investigate the effect of habitual caffeine intake on 5-km cycling time-trial performance following the ingestion of caffeinated coffee. Following institutional ethical approval, in a double-blind, randomized, crossover, placebo-controlled design, 46 recreationally active participants (27 men and 19 women) completed a 5-km cycling time trial on a cycle ergometer 60 m in following the ingestion of 0.09 g/kg coffee providing 3 mg/kg of caffeine, or a placebo. Habitual caffeine consumption was assessed using a caffeine consumption questionnaire with low habitual caffeine consumption defined as <3 and ≥6 mg · kg-1 · day-1 defined as high. An analysis of covariance using habitual caffeine intake as a covariant was performed to establish if habitual caffeine consumption had an impact on the ergogenic effect of coffee ingestion. Sixteen participants were classified as high-caffeine users and 30 as low. Ingesting caffeinated coffee improved 5-km cycling time-trial performance by 8 ± 12 s; 95% confidence interval (CI) [5, 13]; p < .001; d = 0.30, with low, 9±14 s; 95% CI [3, 14]; p = .002; d = 0.18, and high, 8 ± 10 s; 95% CI [-1, 17]; p = .008; d = 0.06, users improving by a similar magnitude, 95% CI [-12, 12]; p = .946; d = 0.08. In conclusion, habitual caffeine consumption did not affect the ergogenicity of coffee ingestion prior to a 5-km cycling time trial.
越来越多的证据表明，运动前摄入咖啡因和咖啡能提供相似的增强运动表现的益处。然而，长期以来一直存在一种观点，即习惯性咖啡因摄入可能会影响咖啡因补充的增强运动表现的效果。本研究的目的是调查习惯性咖啡因摄入对摄入含咖啡因咖啡后 5 公里自行车计时赛表现的影响。在机构伦理审查批准后，采用双盲、随机、交叉、安慰剂对照设计，46 名有规律参加体育活动的参与者（27 名男性和 19 名女性）在服用 0.09g/kg 提供 3mg/kg 咖啡因的咖啡或安慰剂 60 分钟后，在固定自行车测功计上完成 5 公里自行车计时赛。使用咖啡因摄入量问卷评估习惯性咖啡因摄入量，将低习惯性咖啡因摄入量定义为 <3mg·kg-1·day-1，将高习惯性咖啡因摄入量定义为≥6mg·kg-1·day-1。采用协方差分析，将习惯性咖啡因摄入量作为协变量，以确定习惯性咖啡因摄入是否对咖啡摄入的增强运动表现效果产生影响。16 名参与者被归类为高咖啡因使用者，30 名参与者被归类为低咖啡因使用者。摄入含咖啡因的咖啡将 5 公里自行车计时赛的表现提高了 8 ± 12 秒；95%置信区间（CI）[5，13]；p <.001；d = 0.30，低咖啡因使用者提高了 9 ± 14 秒；95%CI [3，14]；p =.002；d = 0.18，高咖啡因使用者提高了 8 ± 10 秒；95%CI [-1，17]；p =.008；d = 0.06，低咖啡因和高咖啡因使用者的提高幅度相似，95%CI [-12，12]；p =.946；d = 0.08。总之，习惯性咖啡因摄入并不影响 5 公里自行车计时赛前摄入咖啡的增强运动表现效果。
