UGent - How caffeine improves sports performance: A scientific look at this uplifting substance

Caffeine is ubiquitous in our daily lives: it's in our morning coffee, in a nice hot tea, a can of cola, energy drinks (e.g. Red Bull), even in a piece of chocolate. But did you know that this everyday substance can also improve sports performance? Caffeine can give that extra push, whether you are an endurance athlete, do strength training or want to be just a little sharper during a competition. In this blog, Dr Helene Schroé, dietician and postdoctoral researcher at the Department of Movement and Sports Sciences (UGent) explains how caffeine can make a difference during exercise. In addition, Etixx offers three handy caffeine products to support you during exercise: Caffeine Energy Shots, Caffeine Sport Gummies and the PRO LINE Energy Gel + Caffeine Mango.

The action of caffeine and how it can improve sports performance

That caffeine is a stimulant that can suppress fatigue has been known for centuries. But what exactly are caffeine's mechanisms of action and how can it improve sports performance? The main mechanism mainly acts on the central nervous system (Guest et al., 2021). In terms of structure, caffeine is very similar to adenosine, a body's own substance that transmits fatigue and pain signals. Normally, adenosine binds to receptors in the brain, making us feel tired and lifeless. However, when we ingest caffeine, it takes the place of adenosine, and will block the action of adenosine. The result? Less fatigue, less pain, and more focus, alertness, responsiveness and motivation (Burke, 2008; Sprite, 2014). In addition, there are other physiological mechanisms that may play a role (Guest et al., 2021): caffeine is thought to stimulate the release of endorphins (less pain, increased endurance), it is thought to increase calcium release in the muscle (faster and more powerful muscle contractions), etc.  All factors that can therefore positively influence sports performance.

Scientific research confirms that caffeine can actually boost sports performance. Especially for endurance efforts, the effect is well established in numerous studies (Guest et al., 2021; Maughan et al., 2018). For example, a meta-analysis of 46 studies shows that caffeine intake for efforts of 5 to 150 minutes - such as cycling, running and rowing - on average provides a performance improvement of 2 to 3% compared to a placebo (Southward et al., 2018). But the effect of caffeine is not limited to endurance sports. An increasing number of studies show that caffeine can also improve maximal strength, jumping power and explosive efforts such as sprints. For example, a study by Wiles et al (2006) showed that trained athletes could improve their time on a 1km cycling test by more than 3% after taking caffeine, compared to a placebo. In addition, caffeine appears to improve the performance of both trained and untrained athletes (Guest et al., 2021).

What dose and timing for optimal performance

Research suggests that an amount between 3 and 6 mg per kg body weight is most effective (Guest et al., 2021; Maughan et al., 2018). For an athlete weighing 60 kg, this corresponds to 180-360 mg of caffeine. This dose is ideally taken about 60 minutes before exercise so that the substance reaches its maximum effect during the moment of exercise. The effects usually last for 2-3 hours, meaning that for longer efforts - such as a marathon or a stage in the Tour de France - it may be useful to consider a second dose, or start taking it later. For example, cyclists often take a first dose before the start, and a second dose towards the end of the stage, for example before a decisive climb or sprint. Interestingly, even lower doses (<3 mg/kg) can already offer benefits, especially in terms of concentration, reaction time and mental sharpness (Spriet, 2014). This makes caffeine particularly interesting for team sports or situations where alertness and reaction time are crucial.  Higher doses (>9 mg/kg), on the other hand, are not recommended as they do not provide any additional improvement in performance and they also increase the risk of side effects such as gastrointestinal distress, anxiety, nervousness, insomnia or palpitations (Guest et al., 2021; Maughan et al., 2018; Burke, 2008).

So, although caffeine is available in many forms - from coffee to energy drinks - exact dosage is crucial. Products like coffee are less reliable, as the caffeine content varies greatly depending on the method of preparation, the type of bean and the strength of the coffee. So for athletes, supplements with pure caffeine - such as capsules, gels, sweets or shots - are more reliable and practical (Guest et al., 2021). Which one you choose depends on your sport goal and time of intake. Capsules typically contain larger amounts of caffeine (200-300 mg) and are therefore ideal for prolonged efforts (e.g. cycling). Gels and sweets often combine moderate amounts of caffeine (50-100 mg) and also contain carbohydrates, making them suitable during exercise.

Individual differences

So caffeine sounds promising as a performance-enhancing drug, but not everyone reacts the same to caffeine. This is mainly due to genetic differences, especially in the CYP1A2 gene, which determines how fast you break down caffeine. Depending on your genotype, you are someone who metabolises quickly or slowly. Guest et al's (2018) study found that only fast metabolisers (AA genotype) performed better after caffeine intake, while slow metabolisers (CC genotype) performed even worse. So your genes may determine whether caffeine helps you - or not. In addition, regular coffee drinkers are often thought to be less sensitive to the effects of caffeine. Yet, research shows that regular coffee drinking hardly affects the effectiveness of caffeine during exercise (Goncalves et al., 2017). However, regular drinkers may need a slightly higher dose to achieve the same effect. However, this does not mean that caffeine is less effective - just that the optimal amount may differ from person to person. It is therefore not necessary to ‘wean off’ caffeine in the days before a competition (Irwin et al., 2011). On the contrary: suddenly stopping can lead to withdrawal symptoms such as headaches, fatigue or irritability, which can actually undermine your performance.

Therefore, it is important to try caffeine first during training sessions, so that athletes learn their personal sensitivity and possible side effects well.

Conclusion

Caffeine improves sports performance in both endurance and short, maximal (strength) efforts, especially at a dose of 3-6 mg/kg body weight taken about 60 minutes before exercise. Effectiveness varies from person to person and should be tested individually. Please note that more is not better - high doses can cause gastrointestinal distress, anxiety, nervousness, insomnia or palpitations.

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