According to a new study published in Medicine & Science in Sports & Exercise,caffeine can help athletes better perform aerobic work compared to anaerobic exercise.
While more research is needed, our results show that the substance helps you power through tough endurance workouts, says Adriano E. Lima-Silva, Ph.D., an adjunct professor with the human performance research group at Technological Federal University of Paraná in Brazil. "Caffeine could be helpful because it decreases perceived effort over longer periods, which means you will enjoy the exercise more." However, he points out that it wasn’t associated with greater anaerobic work (like heavy weight training, sprinting, or other high-intensity exercises during which you put out maximum effort for less than two minutes).
Caffeinating every time you work out can backfire over time. "It should be only used in a competition or for a particularly hard aerobic workout," Lima-Silva says. "There is some evidence that chronic use of caffeine causes desensitization, so you can miss the ergogenic effect if you use it regularly for more than three to four weeks every training cycle." For best results when you do ingest it, he recommends three milligrams per kilogram of body weight an hour before your workout or race.