Expert opinion: Jack James is Professor of Psychology at Reykjavik University, Iceland, where he teaches and researches in health psychology. Here he tells us why cyclists should watch their caffeine intake

Despite exuberant claims about caffeinated energy drinks and gels, controlled trials show that even under ideal conditions caffeine enhances physical performance by only about one to three per cent.

Admittedly, a boost of that magnitude for a finely tuned elite athlete could mean the difference between winning and losing a race.

For the recreational athlete, however, any such difference is marginal — hardly noticeable among all the other factors affecting performance, including training, nutrition, sleep, and mood.

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Still, why not welcome all the help we can get, even if the science, as opposed to the hype, tells us that the benefit from caffeine is modest?

To begin with, trying to extract the maximum competitive edge from caffeine is never going to be easy. Even low-level caffeine use quickly leads to physical dependence, with the associated risk of withdrawal symptoms, including sleepiness, lethargy and headache.

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Although withdrawal symptoms can be kept at bay by slowly reducing one’s caffeine intake, slip-ups in maintaining this declining level are likely to disrupt training and undermine performance.


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Trying to avoid such slip-ups could lead to an excess amount of the drug being taken, leaving you feeling jittery, anxious, and agitated — or worse.

You could experience a sudden increase in heart rate and suffer cardiac arrhythmia precipitating a seizure.

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Although death from caffeine overdose is unusual, intense physical activity is associated with a disproportionate number of confirmed caffeine-related fatalities.

Caffeine may produce a measure of benefit for some individuals sometimes. On the other hand, disruptive symptoms are likely to result from taking too little or too much caffeine on a given day. What’s more, the risks, though low, are real and serious.

The final verdict on caffeine as an ergogenic aid is clear. Accepting that the benefit of caffeine is small, the risks — both minor and major — indicate that the best course of action for elite and recreational athletes alike is to carefully limit caffeine intake or abstain altogether.