Caffeine

The main functions of caffeine

• Increases energy production.
• Increases fat loss.
• Increases stamina.

Mechanism of action of caffeine

Caffeine has been used for hundreds of years. Although it is not a nutrient, it is widely used in conventional diets. In the process of metabolism, it is converted in the liver into three dimethylxanthines - paraxanthin, theophylline and theobromine.

Three main theories for the ergogenic effect of caffeine are proposed.

• Being a stimulant of the central nervous system, reduces the perception of fatigue.
• Increases muscle contraction due to the beneficial effect on transport of ions.
• It enhances the utilization of fat and thus keeps muscle glycogen.

Since caffeine enters the central nervous system and skeletal muscles, it is impossible to separate its effect on the central nervous system from affecting the peripheral nervous system. Perhaps in different situations for the improvement of indicators meet different mechanisms.

Research results

Interest in caffeine as an ergogenic remedy arose from the work of the Costill laboratory more than 40 years ago. In a 1978 study, nine competing cyclists took 330 mg of caffeine (5 mg-kg-1) one hour before the race at 80% V02max and were able to race 19% longer (90 minutes compared to 75 minutes).

A 1979 study showed that consuming 250 mg of caffeine increased by 20% the amount of work that could be done in two hours. These two studies showed that in experiments with caffeine, the utilization of fat to release energy increased by about 30% . A study in 1980 found that consumption of 5 mg of caffeine-kg-1 reduced the use of muscle glycogen by 42% and increased the use of muscle triglycerides by 150% during a 30-minute bicycle race at 70% V02max.

Subsequent experiments on caffeine and exercise indices produced conflicting results. However, in the last 10 years it has been established that caffeine can increase endurance.

In 1991, Graham, Spriet assessed the effect of caffeine intake on runners and cyclists. Athletes took 9 mg of caffeine-kg-1 for 1 hour before the race and run to exhaustion at an intensity of about 85% V02max. The average endurance increase in running was 44%, and in the bike - 51%. However, caffeine levels in four of the 12 urine samples gave figures close to or above the threshold set by the IOC.

Graham, Spriet conducted another study to examine the effect of different doses of caffeine on well-trained athletes. Eight subjects avoided taking caffeine for 48 hours, then consumed 3, 6 and 9 mg of caffeine per 1 kg of body weight or placebo for 1 hour before loading at 85% V02max. Endurance was increased at doses of 3 and 6 mg-kg-1, but not at a dose of 9 mg-g-1. Epinephrine plasma did not increase at a dose of 3 mg, but increased at high doses. Only a dose of 9 mg revealed an increase in levels of glycerin and free fatty acids.

These data indicate that even the lowest dose of 3 mg-kg-1 exhibits an ergogenic effect without increasing the level of epinephrine.

Recommendations for caffeine consumption

Graham, Spriet believes that consumption of 3-13 mg of caffeine-kg-1 increases endurance by 20-50% in elite athletes and amateurs during cycling or running at 80-90% of V02max.

They indicate that doses of caffeine from 3 to 6 mg-kg-1 for 1 h before the load give an ergogenic effect without raising the level of caffeine in the urine above the doping threshold of the IOC.

Although higher doses of caffeine from 9 to 13 mg-kg-1 also improve athletic performance, they are likely to cause side effects and raise the level of caffeine in the urine above the doping threshold of the IOC (12 μg-dl-1) and HCCA (15 μg- dl-1).

With relative harmlessness of caffeine, its large doses can cause side effects, including nausea, muscle tremors, rapid pulse and headache. Athletes sensitive to caffeine, can experience these symptoms and with small doses.

Athletes should be aware that the ergogenic effects of some proprietary supplements may be the result of caffeine contained in them. Nuts, Paraguayan tea and guarana contain caffeine.