The University of Queensland, School of Human Movement Studies, Australia.
J Sci Med Sport. 2013 Jul;16(4):343-7. doi: 10.1016/j.jsams.2012.08.004. Epub 2012 Sep 7.
To examine the effect of a high carbohydrate meal on serum caffeine concentration following caffeine intake.
Randomised, double-blind, crossover.
Fourteen healthy males randomly completed 4 trials, each separated by 5 days. Participants either remained fasted (on 2 occasions) or ingested a high carbohydrate meal (2.0gkg(-1) carbohydrate, 42.4±0.6kJkg(-1)) prior to consuming either 6 or 9mgkg(-1) anhydrous caffeine. Venous blood was sampled for the analysis of serum caffeine at baseline and at 6 time-points over 4h following caffeine intake.
Peak caffeine concentration occurred 60min following ingestion for both the 6 and 9mgkg(-1) fasted (p<0.001) trials compared to 120 and 180min following ingestion for the 6 and 9mgkg(-1) fed trials, respectively (p<0.001). Peak concentration was greater in the 9mgkg(-1) fasted trial than the corresponding fed condition (70±9μmolL(-1) and 56±6μmolL(-1), respectively) and both were greater than the 6mgkg(-1) conditions (44±8μmolL(-1) and 38±8μmolL(-1) for 6mgkg(-1) fasted and fed, respectively). Area under the caffeine curve was significantly greater (p<0.001) in the 9mgkg(-1) fasted trial (3262μmolL(-1)h(-1)), whilst areas were lowest in the 6mgkg(-1) fed trial (1644μmolL(-1)h(-1)).
A high carbohydrate meal consumed prior to caffeine ingestion significantly reduced serum caffeine concentrations and delayed time to peak concentration. Differences in research findings between caffeine supplementation studies may, at least in part, be related to variations in postprandial timing of caffeine intake. The influence of postprandial timing should be considered when athletes consume caffeine with the aim of enhancing performance.
研究摄入咖啡因后高碳水化合物餐对血清咖啡因浓度的影响。
随机、双盲、交叉。
14 名健康男性随机完成 4 项试验，每项试验间隔 5 天。参与者或禁食（2 次）或摄入高碳水化合物餐（2.0g/kg 碳水化合物，42.4±0.6kJ/kg），然后摄入 6 或 9mg/kg 无水咖啡因。在摄入咖啡因后 4 小时内的 6 个时间点抽取静脉血样，分析血清咖啡因。
与 6mg/kg 禁食和 9mg/kg 禁食相比，6mg/kg 禁食和 9mg/kg 禁食试验中，咖啡因摄入后 60 分钟达到峰值（p<0.001），分别为 120 分钟和 180 分钟（p<0.001）。9mg/kg 禁食试验中的峰值浓度大于相应的进食状态（70±9μmol/L 和 56±6μmol/L），均大于 6mg/kg 条件（6mg/kg 禁食和进食分别为 44±8μmol/L 和 38±8μmol/L）。咖啡因曲线下面积在 9mg/kg 禁食试验中显著增加（p<0.001），而在 6mg/kg 进食试验中最低（1644μmol/L·h）。
摄入咖啡因前摄入高碳水化合物餐可显著降低血清咖啡因浓度并延迟达峰时间。咖啡因补充研究结果之间的差异可能至少部分与餐后摄入咖啡因的时间有关。当运动员为了提高运动表现而摄入咖啡因时，应考虑餐后时间的影响。
