In an article published in the Journal of Pain, researchers theorized that caffeine eases delayed muscle pain by blocking the activity of a chemical called adenosine. Adenosine is released as part of the inflammatory response to injury. It can activate pain receptors in body cells, they say.

The research disclosed that in an experiment conducted, it was discovered that caffeine equal to 2 cups of brewed coffee, taken an hour before the activity, could produce a large reduction in pain resulting from eccentric exercise.