Does caffeine maximize endurance exercise performance?

SOUZA JUNIOR, T. P.; CAPITANI, C. D.; LOTURCO FILHO, I.; VIVEIROS, L.; AOKI, M. S. Does caffeine maximize endurance exercise performance? Brazilian Journal of Biomotricity. v. 6, n. 3, p. 144-152, 2012. Caffeine is commonly ingested by athletes because of its potential ergogenic effects. It has been proposed that caffeine improve physical performance by acting independently, or concurrently, via 3 different mechanisms: 1) an increased mobilization of intracellular calcium, 2) an increase in free fatty acid oxidation, and 3) serving as an adenosine receptor antagonist in the central nervous system. Early studies suggested that the ergogenic effect of caffeine was related to an increase in fatty acid oxidation and subsequent sparing of muscle glycogen. However, recent investigations indicate that caffeine maximizes endurance performance largely through its antagonist effect on adenosine receptors in the central nervous system. Acting through this mechanism, caffeine may modulate central fatigue and influence ratings of perceived exertion, perceived pain, and levels of vigor, all of which may lead to performance improvements. The majority of research has utilized a protocol where caffeine is ingested 60 min prior to the performance test to ensure optimal absorption. However, it has also been shown that caffeine can enhance performance when consumed 15-30 min prior to the test. The use of caffeine in anhydrous form, as compared to a cup of caffeinated coffee, seems to be more efficient to improve endurance performance. In addition, a low-to-moderate dose of caffeine between 3 and 6 mg/kg appears to be sufficient for enhancing performance in a sustained endurance effort.