The University of Queensland, School of Human Movement Studies, Queensland, Australia.
Med Sci Sports Exerc. 2010 Mar;42(3):571-6. doi: 10.1249/MSS.0b013e3181b6668b.
To determine whether a dose-response relationship exists between caffeine and 2000-m rowing performance.
In this randomized, placebo-controlled, double-blind crossover study, 10 competitive male rowers (mean +/- SD: age = 20.6 +/- 1.4 yr, body mass = 87.7 +/- 10.5 kg, height = 186.8 +/- 6.8 cm, (.)VO2peak = 5.1 +/- 0.6 L x min(-1)) consumed 2, 4, or 6 mg x kg(-1) caffeine or a placebo 60 min before completing a 2000-m time trial on a rowing ergometer. The trials were preceded by a 24-h standardized diet (including a light preexercise meal of 2 g x kg(-1) CHO), and subjects were tested preexercise for hydration, caffeine abstinence, and blood glucose concentrations.
Time trial performance was not significantly different across the three caffeine doses or placebo (P = 0.249). After the three caffeine trials, postexercise plasma glucose and lactate concentrations were higher compared with the placebo trial (P < 0.05). Plasma caffeine concentrations after 60 min of ingestion were lower than the values reported previously by others following the same dose, and there was considerable interindividual variation in plasma caffeine concentrations in response to the various caffeine doses.
The large interindividual response to the caffeine doses suggests that individual characteristics need to be considered when administering caffeine for performance enhancement. In addition, preexercise feeding may significantly affect plasma caffeine concentrations and the potential for caffeine to improve performance.
确定咖啡因与 2000 米划船表现之间是否存在剂量反应关系。
在这项随机、安慰剂对照、双盲交叉研究中，10 名有竞争力的男性划船运动员（平均 +/- SD：年龄=20.6 +/- 1.4 岁，体重=87.7 +/- 10.5 公斤，身高=186.8 +/- 6.8 厘米，峰值摄氧量=5.1 +/- 0.6 L x min(-1)）在划船测功仪上完成 2000 米计时赛后 60 分钟内分别摄入 2、4 或 6mg x kg(-1)咖啡因或安慰剂。试验前进行了 24 小时标准化饮食（包括轻运动前餐 2g x kg(-1)CHO），并在运动前测试了运动员的水合状态、咖啡因戒断和血糖浓度。
三个咖啡因剂量或安慰剂对计时赛表现没有显著影响（P = 0.249）。与安慰剂试验相比，三个咖啡因试验后，运动后血浆葡萄糖和乳酸浓度更高（P < 0.05）。摄入 60 分钟后，血浆咖啡因浓度低于其他人在相同剂量下报告的先前值，并且对各种咖啡因剂量的血浆咖啡因浓度存在相当大的个体间变异性。
个体对咖啡因剂量的反应差异很大，这表明在给予咖啡因以提高表现时需要考虑个体特征。此外，运动前进食可能会显著影响血浆咖啡因浓度和咖啡因提高表现的潜力。
