There is some evidence that caffeine
can enhance prolonged endurance exercise, but few studies have examined how caffeine affects intermittent high-intensity exercise performance. A group of New Zealand researchers tested whether caffeine ingestion could enhance the intense physical performance and skill demands of rugby union football. Subjects included high-level rugby union players. They performed a series of high-intensity bouts and skill tests designed to simulate activities of a real game on two occasions. On one occasion they consumed a moderate dose of caffeine (6 mg/kg) equivalent to about 2-3 cups of brewed coffee 70 min before the tests. On another occasion, they consumed a placebo. The order was randomized and double-blind. Caffeine treatment resulted in significant improvements on the order of about 1-3% during sprinting, power, and accuracy tasks.
ingestion was also associated with significantly higher (51%) epinephrine levels, which may explain some of the ergogenic effects. The results indicate that acute caffeine ingestion can enhance high-intensity performance that is often encountered during workouts or game situations.
Stuart GR, Hopkins WG, Cook C, Cairns SP. Multiple effects of caffeine on simulated high-intensity team-sport performance. Med Sci Sports Exerc. 2005 Nov;37(11):1998-2005.