Caffeine is a methylxanthine alkaloid found in many plants. It is extracted from the fruit of more than 60 species of coffee trees. It is also found in some seeds, nuts or leaves of a number of plants native to South America and East Asia. (1)
The caffeine molecule is often used in athletes for its ergogenic effects, i.e. to improve muscle work. In addition, this substance has pharmacological effects stimulating mainly the nervous system and the heart (2).
The use of caffeine is common in the diet of the majority of athletes. The purpose of this use is to facilitate prolonged effort and performance while reducing the subjective impression of effort. At high doses, caffeine is necessarily considered a doping substance. Athletes can obtain this substance in various foods such as :
Nevertheless, the notion of the ergogenic effects of caffeine remains controversial, since this molecule promotes the availability of fatty acids (lipolytic effects) but does not contribute to their oxidation during prolonged effort. A study carried out during a laboratory cycling test showed that the administration of 5mg/kg of caffeine could improve the performance of these cyclists (evaluation by average speed, average and maximum power) (3). However, it was observed that this administration value (5mg/kg of caffeine) is a performance threshold, since even above this dose the sports results recorded remained the same.
Moreover, caffeine is a psychostimulant and may cause various other clinical effects noticed in its consumers. Among these effects are the following:
After ingestion, this substance is rapidly and completely absorbed into the bloodstream, resulting in a fairly rapid increase in its concentration in the blood (which reaches its maximum in 30-90 minutes and decreases on average after 3-5 hours after ingestion) (4).
Energy drinks that contain caffeine are therefore intended to provide immediate energy to the consumer’s body, but remain ineffective in the long term. Caffeine can have a direct effect on the brain, just as it can reduce exercise-related fatigue and pain, so it can be concluded that it can have a positive effect on performance in sportsmen and women, and even more so in people who are not used to its consumption.
It may also improve the reaction time of certain anaerobic exercises, but it has no effect on repeated high-intensity training (5).
Caffeine is one of the most commonly used stimulants in sport. Although many studies have examined the effects of caffeine consumption during exercise, not all of these studies are able to draw conclusions about the ergogenic effects of caffeine on sport performance.