Caffeine (1,3,7-trimethylxanthin) is a stimulant substance contained naturally in leaves, fruits and seeds of various plants, discovered in 1819 by the German chemist Friedrich Ferdinand Runge. Today, many foodstuffs, beverages, and supplements contain high amounts caffeine.
Does Caffeine Improve Sports Performance?
Caffeine is the most widely used and performance enhancing supplement in the world by both athletes and non-athletes, and its ergogenic effect has been studied in various exercise models. So much so that until 2004, it was included in the World Anti-Doping Agency prohibited list due to its performance improving effects. With its removal from the list, many studies have been conducted to determine its ergogenic effects and the appropriate dose that provides these effects. Today caffeine studies have gained a new dimension.
The first finding that caffeine improves exercise performance is based on the study of David Costill et al in the 1970s. Findings of the study showed that caffeine improves endurance performance by increasing fat oxidation and reducing carbohydrate use. However, from the 1970s to the present, it has been shown that the ergogenic effect of caffeine is not due to the increase in fat oxidation and the decrease in glycogen use. Today the accepted opinion is; The main mechanism behind the ergogenic effects of caffeine is its blocking effect on adenosine receptors. This consensus explains the ergogenic effect of caffeine in short-term high-intensity exercise that does not rely on oxidative metabolism of fat and carbohydrate.
The Competition Between Caffeine and Adenosine Molecules
Adenosine is a by-product produced by the neurons. Under normal conditions, when the amount of adenosine in the brain and spinal cord increases above a certain level, it binds to the adenosine receptor and leads to fatigue and sleepiness. Adenosine performs this effect by inhibiting the release of neurotransmitters such as acetylcholine and dopamine. However, caffeine and adenosine have a similar molecular structure and this makes caffeine an adenosine receptor antagonist. In other words, caffeine competes with adenosine molecules to bind to the receptor and can bind to the receptor. However, when caffeine binds to the receptor, it inhibits the receptor rather than activating signaling pathways like adenosine. Thus, the release of neurotransmitters is enhanced and we feel more vigorous, energetic and focused. These effects may contribute to the improvement of sports performance.
What About Adverse Effects?
Although historically the interest in caffeine has been based on its performance enhancing effect, it’s not free of side effects. For example; It is known that caffeine increases anxiety. This may cause pre-competition caffeine consumption to be a performance limiting factor.
In addition, 50% of the caffeine consumed continues to remain in the bloodstream even after 5-6 hours after the consumption, and this can negatively affect both falling asleep and sleep quality. For this reason, effects related to caffeine consumption should be evaluated individually.
Moreover, the genetic diversity we have causes us to respond differently to caffeine consumption. While caffeine consumption results in improved performance in some individuals, it is ineffective in others and may adversely affect performance in some other individuals.