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  • Aiveen Connolly

Myth Busting: Caffeine

What is it?

Caffeine is essentially a stimulant and was previously classed as a banned substance but was then removed from the World Anti Doping Agency (WADA) Prohibited list. Caffeine is

found in many drinks and foods such as coffee, tea, chocolate, cola and herbs. It is added to a lot of energy drinks, sports drinks and gels.

What does it do? Will it improve my performance?

Caffeine acts on the central and peripheral nervous system. It increases alertness and concentration and reduces the perception of effort. There is great evidence that caffeine may enhance the performance in endurance sports (lasting longer than 60mins), high intensity sports (lasting 1-60mins) and team and intermittent sports.

Caffeine can be consumed just before exercise, spread throughout exercise or late in exercise when fatigue starts to occur because the performance benefits occur soon after consuming caffeine.

Do bear in mind that individuals' responses to caffeine vary. Some individuals are more caffeine sensitive while others are not as caffeine sensitive and may not get much of an effect from it so it is important to experiment during training sessions to find the dose and protocol that suits you best.

Do I need it?

There is a lot of research and evidence to suggest caffeine intake can enhance performance for most types of endurance, power and strength activities, taken at doses of 1-3mg/kg. These performance benefits occur soon after consumption. As when changing anything about your diet, it is important to always experiment during training sessions and not coming up or during competition events.

Studies have shown it makes little difference to performance whether caffeine is taken in the form of pills, gels, energy drinks or coffee. Keep in mind caffeine content in coffee can vary greatly depending on the preparation method, brand of coffee and variety.

Are there any side effects?

Low-moderate doses of caffeine can produce positive effects of a sense of wellbeing but higher doses of caffeine can have negative effects. It may increase the heart rate, impair motor control and technique, cause anxiety and impair sleep. However, research shows no link between long term caffeine use and health problems (such as hypertension and bone mineral loss).

There are a number of energy drinks on the market today that contain caffeine which claim to improve some aspect of performance. The evidence is not clear but it is thought that caffeine at doses of 1-3mg per kg may reduce the perception of fatigue and allow you to continue exercising at a higher intensity for a longer period of time.

For example, a 70kg person would have to take 210mg of caffeine which is the equivalent to taking 2 cups of coffee or 2 cans of an energy drink containing caffeine to see any effect.

Lets put this into practice... here is the caffeine content of some popular drinks and foods:

Instant coffee - 60mg of caffeine per cup

Espresso - 45-100mg of caffeine per cup

Tea - 40mg of caffeine per cup

Green tea - 40mg of caffeine per cup

Energy drinks - 100mg of caffeine per cup

Dark chocolate - 40mg of caffeine per cup

Milk chocolate - 12mg of caffeine per cup


Gabt, N., Ali A. and Foskett, A. (2010), ‘The influence of caffeine and carbohydrate ingestion on simulated soccer performance’, Int J. Sport Nutr. Exerc. Metab., vol 20. Pp. 191-7

Higgins, S. et al (2015), ‘The effects of pre exercise caffeine are coffee ingestion on endurance performance:an evidence-based review; Int J. Sport Nutr. Exerc. Metab., Nov 16 (Epub ahead of print).

Graham, T. E. and Spriet, L. L. (1995), ‘Metabolic, catecholamine and exercise performance responses to various does of caffeine’, J. Appl. Physical., vol. 78: pp. 867-74

Bean, A,. 2017, Complete Guide to Sports Nutrition. [S.I]: Bloomsbury Sport


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