Int J Sports Physiol Perform. 2019 Apr 1;14(4):426-431. doi: 10.1123/ijspp.2018-0458. Epub 2019 Feb 19.
To investigate the influence of torque factor and sprint duration on the effects of caffeine on sprint cycling performance.
Using a counterbalanced, randomized, double-blind, placebo-controlled design, 13 men completed 9 trials. In trial 1, participants completed a series of 6-s sprints at increasing torque factors to determine the torque factor, for each individual, that elicited the highest (T) peak power output (PPO). The remaining trials involved all combinations of torque factor (0.8 N·m·kg vs T), sprint duration (10 s vs 30 s), and supplementation (caffeine [5 mg·kg] vs placebo).
There was a significant effect of torque factor on PPO, with higher values at T (mean difference 168 W; 95% likely range 142-195 W). There was also a significant effect of sprint duration on PPO, with higher values in 10-s sprints (mean difference 52 W; 95% likely range 18-86 W). However, there was no effect of supplementation on PPO (P = .056). Nevertheless, there was a significant torque factor × sprint duration × supplement interaction (P = .036), with post hoc tests revealing that caffeine produced a higher PPO (mean difference 76 W; 95% likely range 19-133 W) when the sprint duration was 10 s and the torque factor was T.
The results of this study show that when torque factor and sprint duration are optimized, to allow participants to express their highest PPO, there is a clear effect of caffeine on sprinting performance.
研究扭矩因子和冲刺持续时间对咖啡因对冲刺自行车性能影响的影响。
采用平衡、随机、双盲、安慰剂对照设计，13 名男性完成了 9 项试验。在试验 1 中，参与者以递增的扭矩因子完成了一系列 6 秒冲刺，以确定个体产生最高（T）峰值功率输出（PPO）的扭矩因子。其余试验涉及扭矩因子（0.8 N·m·kg 与 T）、冲刺持续时间（10 s 与 30 s）和补充剂（咖啡因[5 mg·kg]与安慰剂）的所有组合。
扭矩因子对 PPO 有显著影响，T 时的数值更高（平均差异 168 W；95%可能范围 142-195 W）。冲刺持续时间对 PPO 也有显著影响，10 秒冲刺的数值更高（平均差异 52 W；95%可能范围 18-86 W）。然而，补充剂对 PPO 没有影响（P=0.056）。尽管如此，仍存在扭矩因子×冲刺持续时间×补充剂的交互作用（P=0.036），事后检验显示，当冲刺持续时间为 10 秒且扭矩因子为 T 时，咖啡因可使 PPO 更高（平均差异 76 W；95%可能范围 19-133 W）。
本研究结果表明，当优化扭矩因子和冲刺持续时间以允许参与者表达其最高 PPO 时，咖啡因对冲刺性能有明显影响。
