The International Society of Sports Nutrition has a new position paper on caffeine and performance. The highlights:
Caffeine is effective for enhancing sport performance in trained athletes when consumed in low-to-moderate dosages (~3-6 mg/kg). Higher dosages do not result in additional performance benefits.
Caffeine exerts a greater ergogenic effect when consumed in an anhydrous state as compared to coffee.
Caffeine has been shown to enhance vigilance during bouts of extended exhaustive exercise, as well as periods of sustained sleep deprivation.
Caffeine is ergogenic for sustained maximal endurance exercise and has been shown to be highly effective for time-trial performance.
Caffeine supplementation is beneficial for high-intensity exercise.
The literature is equivocal on caffeineâ€™s benefit in strength-power performance.
The scientific literature does not support caffeine induced dieresis during exercise or any harmful change in fluid balance that would negatively affect performance