Caffeine taken before exercise may keep providing a performance boost for several hours, according to a small new study.
Researchers found that caffeine improved repeated cycling sprint performance for at least 3.5 hours after participants took it. But there are some important reasons not to treat the findings as a caffeine prescription: The study, published in Medicine & Science in Sports & Exercise, included only 12 healthy young adults, tested one specific type of intense exercise and used a relatively high dose of caffeine.
Caffeine is already widely used before exercise, and its ability to improve some types of athletic performance is well established. Researchers at the University of Tsukuba in Japan wanted to answer a more practical question: How long can those effects last?
Participants received either caffeine or a placebo 60 minutes before exercising. The caffeine dose was based on body weight at 5.5 milligrams per kilogram.
For perspective, that would be about 374 milligrams of caffeine for a 150-pound person and about 449 milligrams for a 180-pound person. That's important context because the amount tested was considerably more than many people might consume in a typical cup of coffee.
Over the next 3.5 hours, participants completed a series of short, intense cycling tests. Researchers measured how much power they generated and tracked several physical responses to the exercise. They also asked participants how difficult the exercise felt and how much muscle pain they experienced.
Caffeine improved both average and peak cycling power compared with the placebo, and the performance benefit was still apparent 3.5 hours after participants consumed it.
Participants also reported that the exercise felt easier and that they experienced less leg muscle pain after taking caffeine. Researchers observed other changes in the body's response to exercise, but the study wasn't designed to show that those changes caused the improvement in performance.
The findings offer a closer look at how long caffeine's performance effects can persist, but they don't tell us whether the same thing would happen during a typical trip to the gym.
The researchers tested repeated cycling sprints in a very small group of young adults. The study can't establish whether caffeine would provide the same sustained benefit during weight training, a recreational run, a fitness class or other types of exercise. It also can't tell us whether people of different ages would respond similarly.
And the results don't mean that taking more caffeine will produce a better workout. People can respond differently to caffeine, and this study tested a specific dose under controlled conditions rather than comparing different amounts.
Still, the study adds an interesting piece to what we know about one of the world's most commonly consumed stimulants. For certain kinds of intense, repeated exercise, caffeine's performance boost may stick around for hours after that pre-workout dose.
Funding information for the study was not publicly available.