Introductory remarks

Caffeine is a unique compound. It is a drug with no nutritive value so entrenched in our food supply that it enjoys social acceptance and widespread use by the majority of adults around the world. Its well-known effects of reducing fatigue and increasing alertness are prized by populations who need to prolong their capacity for occupational activities, for example, students studying for exams, shiftworkers, long-haul truck drivers, members of the military forces and athletes. In fact, new products such as non-prescription medications, ‘energy drinks’, confectionery and sports supplements containing caffeine or guarana are now being specifically manufactured to allow caffeine to be consumed as an ergogenic (work-enhancing) aid. Although there is a considerable literature on many aspects of the metabolism, pharmacology and uses of caffeine, this review will focus on the use of caffeine in the athletic world.

Caffeine

LM Burke, LL Spriet

Caffeine (C₈H₁₀N₄O₂) has been used as an aid to sports performance for more than a century and has been widely studied by exercise scientists for the past 40 years. From 1980 to 2003, it was included on the list of substances banned by the International Olympic Committee, with limits on urinary caffeine levels above which caffeine use would be deemed to be a doping offence. These levels were intended to discriminate the intake of large amounts of caffeine—typically, above 6–9 mg/kg of an athlete's body mass (kg BM). In 2004, however, caffeine was removed from the list of prohibited substances and methods of the World Anti-Doping Agency, meaning that athletes who compete under this code can …