Caffeine is one of the most well known and studied supplement on the planet. It has many physiological effects although it has no nutritional value. However, its effects are associated with stimulating the nervous system and hence improving exercise capacity. This ‘stimulant’ has been consumed worldwide for centuries and its effects are recognised by many nations. On the other hand athletes are among the groups of people who are interested in the effects of caffeine in endurance exercises and other physical activities.
The available literature suggests that the benefits of caffeine on performance athletes can be seen when moderate amounts of caffeine is consumed (~3mgkg1 body mass). Also, these benefits are potential for many sports such as in endurance, high intensity activities, and stop-and-go events, there is not much evidence on its direct effect on strength and power activities.
Many studies using moderate to high doses of caffeine (5-9 mg/kg BM) have found ergogenic effects in endurance activities and recognised the effects on the physiological responses to exercise; this include increased heart rate, a doubling of blood catecholamine levels, higher blood lactate levels and also increased blood free fatty acid and glycerol levels in some subjects. On the other hand there are some side effects that could occur such as gastrointestinal upset, mental confusion, nervousness, impaired focus and sleep disturbances. Recent studies have shown that lower doses of caffeine can stimulate an ergogenic effect when consumed prior to exercise in short or long endurance events.
Some practical applications for athletes using caffeine can aid athletes in their performance goals. When considering whether to use caffeine as stimulant, it is recommended athletes to begin with low caffeine doses ~100-200mg, and if higher dose is consumed it does not appear to give additional advantage. However, the response to caffeine is strongly individual, and professional athletes need to see its effect in training before moving to competitions.
Caffeine’s ergogenic effect is independent of habitual caffeine use, training status, diet, gender, hydration status, and exercise modality, but results in the heat are less clear (see Burke et. al., 2013; Spriet, 2014). Also, caffeine can be found and consumed in the form of capsules, coffee, sports and energy drinks, gums, gels, and bars, but mouth rinsing with caffeine is less likely to produce an ergogenic effect. Even not so active individuals use caffeine containing substances in their everyday lives in order to improve their mental alertness or other uses such as pain killers.
Caffeine works by stimulating the central nervous system (CNS), heart, muscles, and the centres that control blood pressure. Caffeine can raise blood pressure, but might not have this effect in people who use it all the time. Caffeine can also act like a “water pill” that increases urine flow. But again, it may not have this effect in people who use caffeine regularly. Also, drinking caffeine during moderate exercise is not likely to cause dehydration.
Additionally, the research on caffeine have determined that lower dose of caffeine ~200mg is ergogenic in different exercise and sport scenarios in recreationally and well-trained individuals men and women. On the other hand, high caffeine doses are associated with unpleasant physiological responses to exercise and additional side effects and do not bring more benefits. The mechanism which explains the ergogenic effect of caffeine is shown from adenosine receptor antagonism in the central nervous system and the peripheral nervous system. However, the administration of caffeine in the form of capsules, tablets and coffee used in research, caffeine can be delivered in many different forms with similar ergogenic effects.
So, to wrap it up, caffeine consumption in normal quantity brings physiological benefits that could aid physically active individuals in their performance as well as not as active individuals in their everyday lives, but higher dose will not boost its effects and contrariwise it may cause adverse effects.
Burke, L., B. Desbrow, and L. Spriet (2013). Caffeine for sports performance. Human Kinetics, Champaign, Illinois, USA.
Spriet, L.L. (2014). Exercise and sport performance with low doses of caffeine. Sports Med. 44:S175-S184.