Bell Douglas G, McLellan Tom M
Defence R&D Canada-Toronto, Toronto, Ontario, Canada M3M 3B9.
J Appl Physiol (1985). 2002 Oct;93(4):1227-34. doi: 10.1152/japplphysiol.00187.2002.
The purpose of the present study was to examine the duration of caffeine's ergogenic effect and whether it differs between users and nonusers of the drug. Twenty-one subjects (13 caffeine users and 8 nonusers) completed six randomized exercise rides to exhaustion at 80% of maximal oxygen consumption after ingesting either a placebo or 5 mg/kg of caffeine. Exercise to exhaustion was completed once per week at either 1, 3, or 6 h after placebo or drug ingestion. Exercise time to exhaustion differed between users and nonusers with the ergogenic effect being greater and lasting longer in nonusers. For the nonusers, exercise times 1, 3, and 6 h after caffeine ingestion were 32.7 +/- 8.4, 32.1 +/- 8.6, and 31.7 +/- 12.0 min, respectively, and these values were each significantly greater than the corresponding placebo values of 24.2 +/- 6.4, 25.8 +/- 9.0, and 23.2 +/- 7.1 min. For caffeine users, exercise times 1, 3, and 6 h after caffeine ingestion were 27.4 +/- 7.2, 28.1 +/- 7.8, and 24.5 +/- 7.6 min, respectively. Only exercise times 1 and 3 h after drug ingestion were significantly greater than the respective placebo trials of 23.3 +/- 6.5, 23.2 +/- 7.1, and 23.5 +/- 5.7 min. In conclusion, both the duration and magnitude of the ergogenic effect that followed a 5 mg/kg dose of caffeine were greater in the nonusers compared with the users.
本研究的目的是检验咖啡因产生促力效应的持续时间，以及该效应在使用该药物者和未使用者之间是否存在差异。21名受试者（13名咖啡因使用者和8名非使用者）在摄入安慰剂或5毫克/千克咖啡因后，以最大耗氧量的80%完成了6次随机的力竭性骑行运动。在摄入安慰剂或药物后的1、3或6小时，每周进行一次力竭性运动。未使用者的运动至力竭时间与使用者不同，未使用者的促力效应更大且持续时间更长。对于未使用者，摄入咖啡因后1、3和6小时的运动时间分别为32.7±8.4、32.1±8.6和31.7±12.0分钟，这些数值均显著高于相应的安慰剂组数值，分别为24.2±6.4、25.8±9.0和23.2±7.1分钟。对于咖啡因使用者，摄入咖啡因后1、3和6小时的运动时间分别为27.4±7.2、28.1±7.8和24.5±7.6分钟。只有摄入药物后1和3小时的运动时间显著长于相应的安慰剂组试验，分别为23.3±6.5、23.2±7.1和23.5±5.7分钟。总之，与使用者相比，未使用者在摄入5毫克/千克咖啡因后产生的促力效应的持续时间和强度更大。
