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Caffeine and its effect on sports performance in athletes

Caffeine is commonly consumed as part of our diet with an estimated 98 million cups of coffee consumed daily in the UK (British Coffee Association). In addition to coffee, caffeine is also found in tea, fizzy drinks, and chocolate. Many people have caffeine for its taste and as a pleasurable drink, but it can also be beneficial for cognitive and physical performance. In this article I will explore how caffeine may help to improve your performance.

Firstly, how can caffeine improve performance?

Caffeine is a stimulant. It causes our central nervous system to increase activity. The central nervous system is responsible for controlling most of the functions in the body. Caffeine stimulates the central nervous system because it has molecules which are similar to those found naturally in our bodies. Through this stimulation we become more alert and energised. This therefore provides a benefit for both exercise and performance.

Most of the research for caffeine use in sport is based on its benefits for endurance exercise. The International Society of Sports Nutrition report that caffeine consistently improves endurance performance by 2-4%. Sports in which caffeine consumption has been frequently studied include cycling, running, and swimming. However, this does not mean that caffeine is only advantageous for endurance exercise. Although the evidence is less strong, caffeine may also improve performance in strength-based exercise, jumping, and high intensity exercise. Caffeine may therefore be beneficial to improve performance in many sporting disciplines.

Of course, the other benefit to caffeine is its effect on brain function. By increasing attention, alertness, and reaction time, caffeine might improve your sporting performance.

So, caffeine can improve both cognitive and exercise performance but how much caffeine is recommended?

Most studies have found a benefit to 3-6mg of caffeine per kg body weight. This dose of caffeine is best taken 60minutes prior to performance as this is likely when caffeine concentration will have peaked in the blood. You should remember however that it is recommended that we consume a maximum of 400mg of caffeine daily. This restriction on caffeine intake is related to its potential to increase heart rate and blood pressure and its potential to cause disorientation and vomiting. Therefore, before you take a caffeine supplement consider how much caffeine you are already consuming to ensure you are not having excessively high caffeine intakes. Below is a list of some caffeine containing foods and their estimated caffeine content:

Espresso shot

  • 92mg


  • 277mg

Medium Latte

  • 185mg

Medium cappuccino

  • 277mg

Flat white

  • 277mg

Cup of tea

  • 47mg

70-85% dark chocolate (100g)

  • 80mg

Along with these commonly consumed foods, caffeine is also available as a capsule supplement, powder, gum, and in energy gels and drinks. The research for caffeine in performance is mostly based on capsules and powders due to ease for study designs. An important consideration for all of these options is that they may be absorbed by our bodies at different times and so the time in which you take them prior to exercise should be considered. For example, caffeinated gums are absorbed quicker than caffeinated drinks and therefore should be taken closer to the beginning of exercise.

As with all sports supplements, the effect of caffeine on performance can vary between individuals. Our genetic makeup can alter how our bodies breakdown caffeine and so some individuals will respond to lower doses of caffeine while others while require a higher dose for caffeine to have an effect. Our body’s response to caffeine can also be impacted by the amount of caffeine you usually consume. Our bodies can adapt to caffeine intake and so those of us who regularly have a high caffeine intake are likely to require a higher caffeine dose to stimulate an effect.

Not only does this individual response have an impact on what dose of caffeine we need to impact performance, it will also impact how we experience the side effects of caffeine. Caffeine can cause irritability, restlessness, acid reflux, and diarrhoea. Additionally, it can increase anxiety which is not desired particularly before matches or competitions when you may already be anxious. Caffeine has also been noted to interfere with sleep as caffeine concentration can remain elevated in the blood for several hours. Therefore, by having caffeine prior to exercise to improve performance you may impact recovery and future performance which is not desirable. It is therefore advisable that you consider the timing at which you are having caffeine.

In summary, caffeine has been shown to improve both exercise and cognitive function but like all sports supplements, if you choose to take a caffeine supplement trial and error is required to find a dose which works for you.

If you would like individualised advice regarding sports supplementation, please speak to one of our sports dietitians


Guest, N.S., VanDusseldorp, T.A., Nelson, M.T. et al. International society of sports nutrition position stand: caffeine and exercise performance. J Int Soc Sports Nutr 18, 1 (2021).

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