Abstract

Caffeine is the most commonly consumed central nervous system stimulant worldwide resulting in increased alertness, mood, arousal, vigilance, and attention. Caffeine is also one of the few permitted ergogenic aids with well-established performance benefits and therefore is used extensively by athletes. Research supports its effectiveness in a broad range of exercise modalities, including sprint, power, intermittent, and endurance activities. For this reason, there has been intense interest in understanding the timing, dose response, biochemistry, and mechanisms of caffeine's action related to sports performance. This chapter will provide an overview of the pharmacokinetics of caffeine, including metabolism and excretion. Caffeine's role in exercise performance encompassing both aerobic and anaerobic activities will be covered in the context of physiological impacts and performance measures. Current recommendations regarding effective dose, timing, and alternative modes of administration are provided. Mechanisms of action, including adenosine receptor antagonism, skeletal muscle function, and carbohydrate and fat oxidation, are reviewed. Concerns regarding caffeine ingestion and potential negative side effects are highlighted, as well as the need for individualized recommendations. Factors that could affect an athlete's response to caffeine, including biological sex, habituation, and genetics, are discussed. Finally, unanswered questions and future directions are included to show limitations in our knowledge.