Somayeh Taherkhani - Master of sports physiology, nutrition major, Allameh Qazvini Institute of Higher Education, Qazvin, Iran

Caffeine is a drug that stimulates (increases the activity of) your brain and nervous system. Caffeine is found in many drinks such as coffee, tea, soft drinks and energy drinks. Caffeine slows down the body's depletion of glycogen. This action is done by encouraging the body to use stored fat in the body as a fuel source, which makes the exercise continue for a longer period of time. Due to the rapid depletion of glycogen resources, especially in endurance sports, athletes gain many benefits from caffeine consumption. Activities such as running, cycling, and skiing that last more than an hour and require maintaining peak athletic performance during training, caffeine allows athletes to increase their endurance, accuracy, and speed. Unlike endurance sports, caffeine has no significant effect on strength and power activities such as weightlifting. Caffeine is a popular work-enhancing supplement that has been actively researched since the ۱۹۷۰s. The majority of research has examined the effects of moderate to high caffeine doses (۵–۱۳ mg/kg body mass) on exercise and sport. These caffeine doses have profound effects on the responses to exercise at the whole-body level and are associated with variable results and some undesirable side effects. Low doses of caffeine (<۳ mg/kg body mass, ~۲۰۰ mg) are also ergogenic in some exercise and sport situations, although this has been less well studied. Lower caffeine doses (۱) do not alter the peripheral whole-body responses to exercise; (۲) improve vigilance, alertness, and mood and cognitive processes during and after exercise; and (۳) are associated with few, if any, side effects. Therefore, the ergogenic effect of low caffeine doses appears to result from alterations in the central nervous system. However, several aspects of consuming low doses of caffeine remain unresolved and suffer from a paucity of research, including the potential effects on high-intensity sprint and burst activities. The responses to low doses of caffeine are also variable and athletes need to determine whether the ingestion of ~۲۰۰ mg of caffeine before and/or during training and competitions is ergogenic on an individual basis.

Caffeine, Combat sports, Judo, Physical performance, Special Judo Fitness Test.