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SPRING 2004
Caffeine Reduces Exercise Pain
by Michael Childs

That cup of coffee in the morning does more than wake you up. It can also help you feel less pain during your morning workout.

In a study published last August in the Journal of Pain, researchers reported that caffeine reduced thigh muscle pain during cycling exercise.

Participants in the study, 16 nonsmoking young adult men, cycled for 30 minutes on two separate days. The exercise intensity was the same on both days and purposefully set to make the riders’ thigh muscles hurt.

The cyclists took either a caffeine pill or a placebo one hour before the exercise. They reported feeling substantially less thigh pain after taking caffeine compared with the placebo.

This suggests that prior reports showing that caffeine improves performance during endurance exercise might be explained in part by caffeine’s hypoalgesic or pain reducing properties, said Patrick O’Connor, UGA professor of exercise science and a member of the research team.

“Not all analgesics or combinations [such as acetaminophen and caffeine] are effective for every type of pain or every individual,” he said. “Much of this is due to biological variation among people in receptors for the drugs as well as variation in pain receptors in different body tissues.”

Caffeine also seems to work less well for heavy caffeine users, O’Connor said. The research team previously had learned that aspirin, though commonly used to treat muscle pain, did not reduce pain produced by vigorous exercise.

“Muscle contractions produce a host of biochemicals that can stimulate pain. Aspirin blocks only one of those chemicals,” O’Connor said. “Apparently the biochemical blocked by aspirin has little role in exercise-induced muscle pain.”

“The next step is to learn how caffeine helps people feel less muscle pain during exercise,” said the study’s lead author, Robert Motl, a University of Illinois kinesiology professor. “Evidence suggests that caffeine works by blocking the actions of adenosine, however, we don’t know yet whether the caffeine is acting on muscles or the brain.”

For more information, contact Patrick O’Connor at poconnor@coe.uga.edu.