Caffeine has been used as a performance aid for a long time. Prior to 2004, it was on the International Olympic Committee list of banned substances. Caffeine was not banned entirely however there was a tolerance limit in place.
Caffeine has been used as a stimulant since Paleolithic times. It is a naturally occurring substance, found in coffee beans, tea leaves, cocoa beans and cola nuts and it is now the most widely consumed drug in Europe and America.