Caffeine and sports performance
Caffeine is the most popular drug consumed worldwide, approximately 80% of the worldwide population consumes caffeine. It is found in more than 60 plants (in the beans, leaves or fruits) and the main source of caffeine in the human diet are coffee beans and tea leaves.
Caffeine is rapidly absorbed in the intestinal tract and metabolized in the liver through enzymatic reactions mediated by cytochrome P450 that produce three metabolites (paraxanthine, theophylline, and theobromine) that together with caffeine can also influence athletic performance. The amount of caffeine increases notably in the bloodstream after 15 to 45 minutes of consumption, reaching the highest level around 60 minutes. Caffeine levels are reduced by 50 to 75% within 3 to 6 hours after consumption.
One primary caffeine’s site of action is the central nervous system, due to its liposoluble it crosses the blood-brain barrier without difficulty. Furthermore, caffeine also exerts its effects on the peripheric nervous system and the skeletal muscle.
HOW CAFFEINE IMPROVE EXERCISE PERFORMANCE?
Researchers have indicated that during exercise caffeine can decrease glycogen utilization and increase dependence on free fatty acid mobilization improving significantly the performance.
Caffeine acts as an antagonist of adenosine receptors. Adenosine is a neurotrasmisor that transfers the signals related to drowsiness and exertion, thus caffeine reverts the fatigue induced by exercise. Moreover, adenosine inhibits the release of dopamine, thereby reducing mental alertness and motivation, thus caffeine consumption before exercise reverts this effect enhancing dopamine availability and improving alertness and motivation during exercise.
The increase in endorphins induced by coffee consumption has also been associated with a decrease in pain reception due to its analgesic properties.
It has been shown that moderated doses of caffeine (6 mg/kg) can alter neuromuscular function and skeletal muscular contraction.
There are recent studies that suggest that caffeine may influence post-exercise recovery. However, the underlying mechanism is unclear.
Not all people respond equally to caffeine and show the same beneficial effects on sports performance. There are several factors that can interfere with physical performance, such as training level, habitual daily caffeine intake/tolerance to caffeine, and genetic variations. It has been seen that the presence of certain polymorphisms in the genes that encode for liver enzymes, involved in the metabolism of caffeine and other substances, could explain part of these differences.
Gene or region studied