The Mythology: Increases endurance and capacity for intensity. Burns the fat.
The Truth: Reduces fatigue and improves performance, but not everyone benefits.
Research: Caffeine is the most widely used drug in the world and despite decriers its safety profile is enviable. The research regarding endurance sports is unanimous. Yes it works and works well. Marathoners with a Red Bull fix will definitely be able to run longer than their non-caffeinated brethren. The difficulty is with short, high intensity activity like weight lifting and sprinting.
1. Caffeine does seem to improve weightlifting performance, but some may benefit some more than others. This could relate to differential metabolism due to genetics in different individuals.
2. Performance during repeated high-intensity efforts may be diminished with caffeine intake. Some thing that high volume trainers may want to be aware of.
4. Elite athletes and lifters who don’t normally consume caffeine stand to benefit the most.
5. Benefits of caffeine for purely strength-based exercise such as power lifting are minimal.
6. Caffeine reduces perceived exertion
Fat Burning: The evidence so far in humans is not as robust but its far from disappointing. There is tantalizing evidence from animal models and the physiological mechanisms are solid. Furthermore the lack of solid evidence could be attributed to the conduct of the studies themselves and marked individual variability to the effects of caffeine.
1) Schneiker KT, Bishop D, Dawson B, Hackett LP. Med Sci Sports Exerc. 2006 Mar;38(3):578-85.Effects of caffeine on prolonged intermittent-sprint ability in team-sport athletes.
2) Graham TE, Battram DS, Dela F, El-Sohemy A, Thong FS, Appl Physiol Nutr Metab. 2008 Dec;33(6):1311-8. Does caffeine alter muscle carbohydrate and fat metabolism during exercise?
2)Hursel R, Westerterp-Plantenga MS, Int J Obes (Lond). 2010 Apr;34(4):659-69. Epub 2010 Feb 9. Thermogenic ingredients and body weight regulation.
How it works: Mechanism is adenosine receptor antagonism, and possibly enhanced fat metabolism which spares glycogen stores. It stimulates the Central Nervous System increasing focus and alertness.
Adverse effects: Dependency; withdrawal; CNS stimulant effects; mild diuretic (but exercise diminishes this effect)