We’ve all heard about the benefits of caffeine consumption for cyclists, and in fact it is the most effective legal performance enhancer out there! Studies have found that caffeine, when taken in the right dose, can improve performance by on average 4%. That’s one big performance gain! But how does it work and how much do we need to take? Let’s find out.
How does caffeine improve performance?
There are several mechanisms to how caffeine improves performance. Firstly, caffeine can bond to adenosine receptors. Adenosine is released from the breakdown of Adenosine Triphosphate (ATP) which is how we produce all the energy within our body. The adenosine molecules then bind to adenosine receptors which then send signals to the brain telling it that we are experiencing fatigue and reducing our capacity to perform exercise. Caffeine can bond to these receptors in place of adenosine, preventing the signals from passing to the brain and thus reducing the onset of fatigue perception. This is the mechanism that is suggested to be the main performance enhancer of caffeine consumption in aerobic exercise, but also improves anaerobic performance as well along with other mechanisms.
Another area that caffeine has been found to have a small impact on performance is the increased utilisation of fat during exercise. The effects are small, with fat oxidation in g/min increasing from ~0.25g/min up to ~0.38g/min at 40% VO2max. (Gutiérrez-Hellín et al., 2018) while FatOx was also present at higher intensities up to ~70% VO2max. In addition to this, caffeine has been thought to increase the levels of epinephrine (adrenaline) by increasing overall levels of catecholamine. The increase of this can enhance the amount of fat the body oxidises, which in conjunction with the breakdown of triglycerides (how fats are stored) into usable fatty acids, this is the supposed mechanism for how caffeine improves fat oxidation. This could have a small impact both on fat utilisation, body composition enhancement, and also muscle glycogen sparing, but the effect in this regard is small and not as substantial as the other benefits associated with caffeine.
Calcium release is another benefit associated with caffeine consumption. Calcium is essential for muscle contractile as calcium causes a shift in the position of the troponin complex on actin filaments, which exposes myosin-binding sites (Kuo & Ehrlich, 2015). Essentially, the two muscle filaments can’t attach to each other and contract without calcium. This can potentially increase the maximal force production within the muscles (the anaerobic component). Interestingly, a systematic review by Mielgo-Ayuso et al., (2019) found that there were differences in how caffeine affects performance in men and women. It was found that particularly in the anaerobic performance gains, men experienced a higher performance increase than women in several studies. However there were far fewer statistical differences between men and women when looking at the effect of caffeine on aerobic performance and fatigue.
One final benefit of caffeine is the reduction in tiredness and increased levels of alertness. Particularly in a road race, where there is an element of mental fatigue when navigating the peloton, caffeine can reduce tiredness and mental fatigue, in part in the same way that it reduces central fatigue via adenosine binding site blocking.
Where do we get caffeine?
There are many foods and drinks that we can consume which contain caffeine. Coffee is likely the one we are all aware of, but tea (black and green) contains caffeine as does dark chocolate. The amounts vary but in general a single espresso contains 60mg of caffeine with a brewed coffee being closer to 95mg, Black tea 47mg and Green tea 28mg, dark chocolate can have about 25mg per serving, while energy drinks and shots can contain between 170-220mg of caffeine per serving.
How much caffeine should we take?
The recommended amount of caffeine for sports performance is 3-6mg/kg of body mass (Guest et al., 2021) with the performance enhancement from this being on average ~4% with variation either side of this. To put that into perspective, for a 70kg individual, that means that they should be consuming between 210-420mg of caffeine before exercise. That’s 4+ espressos! It is worth noting that minimal caffeine consumption required for performance can be as low as 2mg/kg but this is unclear and will not result in much gain for some individuals. Also, beyond 9mg of caffeine some people do experience negative side effects to the point that the performance enhancement is negated. The overall consensus is that individuals test different caffeine consumption amounts on themselves to balance the positive performance enhancements with what they can tolerate.
In terms of timings, it is recommended that you consume this caffeine 60min pre exercise as that is generally how long it takes to have an effect. However, caffeine gum has been found to act faster, within 30 minutes, but there is debate over how long the effectiveness of caffeine delivered this way lasts. In general, the effects last for around 4 hours, due to caffeine having a half life of 4 hours. After this point, in longer events say, it is beneficial to top-up with a caffeine supplement such as a gel or an energy drink
What side effects can caffeine have?
The side effects of caffeine vary significantly due to the fact that they are often attributed with genetic variance in caffeine metabolism. However, with calcium release being stimulated, this can have a small impact on bone mineral density so it is important to consider factors such as energy availability being adequate and calcium consumption within the diet.
It has also been suggested that caffeine can contribute to dehydration due to it being a diuretic , however the liquid that is consumed along with caffeine in most of the forms that it can be consumed counters this additional fluid loss.
In higher doses, such as 9mg/kg, it has been found that caffeine can increase anxiety and cause shaking in the hands. This highlights why it is important to monitor the amount that you consume, but also be aware of the individual effect that caffeine has on you, as everyone responds to it differently.
Caffeine also has the effect of increasing blood lactate. Now this is not an issue, as lactate is then used as a fuel source potentially increasing overall energy production capacity. However, it is worth bearing in mind if you monitor your lactate levels in training that consuming caffeine will give a higher lactate reading at relative exercise intensities.
One area people often assume caffeine has an effect is heart rate, normally that it increases it. Interestingly, studies have found the opposite in sub-maximal exercise with caffeine consumption decreasing heart rate by 4-7 BPM (McClaran & Wetter, 2007). However, it was found that at rest and maximal exercise intensities, heart rate was not affected significantly. In terms of blood pressure, caffeine consumption did increase systolic pressure at rest, but had no effect during exercise.
Finally, there is often the effect on sleep. Some people find caffeine has virtually no effect on their sleep, while others experience significantly worse sleep. A good rule of thumb is to stop consuming caffeine between midday and 3pm, depending on bed time. This allows plenty of time for the 4 hour half-life of caffeine to reduce its presence in the body and limit its effect on sleep.
An interesting and hotly debated area in caffeine supplementation for performance is caffeine tapering. Many athletes go by the basis that to get the full effectiveness of caffeine on race day they need to reduce the intake of it leading up to the event so as to reduce the resilience to its fatigue reducing mechanisms. However, the research around this topic is highly varied.
A study by Lara et al., (2019) found that continued caffeine supplementation over several days did lead to increased performance over a placebo. However, this magnitude of improvement decreased as the study went on suggesting a progressive tolerance.
Although another recent study found caffeine tapering not to be effective at enhancing performance gains from caffeine supplementation (de Souza Gonçalves et al., 2017). This study however did use 6mg/kg of caffeine supplementation which was significantly higher than what many participants habitually consumed. This is supported by a very recently published meta analysis on the subject by Carvalho et al., (2022) where the conclusion based on 60 studies was that “Habitual caffeine consumption does not appear to influence the acute ergogenic effect of caffeine.”
What we can potentially infer from these studies is that ‘it depends’. But, for the sake of practical recommendations and what studies have looked into, it appears that habitual caffeine use can blunt the effects of caffeine when consumed in the regular daily amount used habitually. So if you consume 3mg/kg/day and then take that amount on competition day, there may be limited benefit. But if you habitually take 3mg/kg/day and then use 6mg/kg on the day of an event, there may be a significant performance benefit.
It is also worth considering the fact that caffeine is essentially an addictive drug, which does mean that reducing the consumption of it from habitual to cold-turkey can cause side effects such as headaches and drowsiness (Graham, 2001). With this in mind, for sports performance you don’t need to stop your caffeine intake entirely, but perhaps reduce it to 2-3mg/kg/day and then supplement with 4-6mg/kg on competition day.
What does this mean for you?
In practical terms, for enhanced sports performance you should aim for between 3-6mg/kg of body mass, for some they may be fine with 2mg/kg. However, caffeine can have a negative effect on performance for some individuals, even at the lower levels. This is why it is vital to test caffeine consumption during training to determine the effect that it has on you and what level you should be consuming to be optimal for your performance. It is also recommended not to consume it after 3pm, possibly midday for some individuals so as not to affect sleep.
Gutiérrez-Hellín, J., & Del Coso, J. (2018). Effects of p-Synephrine and Caffeine Ingestion on Substrate Oxidation during Exercise. Medicine and science in sports and exercise, 50(9), 1899-1906.
McLellan, T. M., Caldwell, J. A., & Lieberman, H. R. (2016). A review of caffeine’s effects on cognitive, physical and occupational performance. Neuroscience & Biobehavioral Reviews, 71, 294-312.
Kuo, I. Y., & Ehrlich, B. E. (2015). Signaling in muscle contraction. Cold Spring Harbor perspectives in biology, 7(2), a006023.
Mielgo-Ayuso, J., Marques-Jiménez, D., Refoyo, I., Del Coso, J., León-Guereño, P., & Calleja-González, J. (2019). Effect of caffeine supplementation on sports performance based on differences between sexes: a systematic review. Nutrients, 11(10), 2313.
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Lara, B., Ruiz-Moreno, C., Salinero, J. J., & Del Coso, J. (2019). Time course of tolerance to the performance benefits of caffeine. PLoS One, 14(1), e0210275.
de Souza Gonçalves, L., de Salles Painelli, V., Yamaguchi, G., de Oliveira, L. F., Saunders, B., da Silva, R. P., … & Gualano, B. (2017). Dispelling the myth that habitual caffeine consumption influences the performance response to acute caffeine supplementation. Journal of applied physiology.
Carvalho, A., Marticorena, F. M., Grecco, B. H., Barreto, G., & Saunders, B. (2022). Can I have my coffee and drink it? A systematic review and meta-analysis to determine whether habitual caffeine consumption affects the ergogenic effect of caffeine. Sports Medicine, 52(9), 2209-2220.
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