Caffeine is one of the world’s most widely used performance enhancing drugs. Its use within sport is also completely legal, and research tends to indicate that about 75% of all athletes consume some form of caffeine before competition. This should come as no surprise; caffeine reliably improves endurance performance, and, whilst its effects on power and strength performance are less clear, it’s certainly not negative.
Caffeine Fuels the World
Caffeine is unique in that its use is ubiquitous amongst athletes and non-athletes alike; I can’t think of any other “supplement” that is widely used by all types of people. There are a variety of ways that we can consume caffeine. For its performance enhancing effects, athletes tend to consume caffeine either as a tablet, or as part of a sports supplement. Non-athletes – and athletes outside of training hours – tend to consume caffeine primarily through coffee as part of their lifestyle. Other regular sources of lower doses of caffeine include various teas and sodas, as well as chocolate.
This leads to a situation where an athlete might use caffeine regularly throughout the day, including a cup or two of coffee in the morning, a large dose through supplements pre-training, and then an additional cup of coffee or caffeinated soft drink following training. It is well established that with regular use of a number of drugs and supplements, our bodies develop a tolerance, requiring greater and greater amounts for the same effect. We can see this anecdotally; people who regularly consume coffee tend to consume more of it as they age in order to see the same stimulating effects, whilst individuals who have never previously consumed caffeine tend to see a huge buzz with very small amounts. Regular use, then, builds up tolerance to caffeine.
It’s easy to see how this could be applied to sport. Because athletes know that caffeine will improve performance, they might start off by taking lower doses, but then gradually transition to higher doses as they seek to recreate the buzz of their first hit. Athletes will also regularly be consuming caffeine, often both for training, but also as part of their lifestyle.
The big question is whether this is a good idea or not; does regular caffeine use by athletes reduce its performance enhancing effects? It’s a simple question, but as always the question is clouded with nuance and context.
Does Regular Caffeine Use Reduce Its Performance Enhancing Effects?
A paper published at the end of last year seemed to suggest that regular caffeine intake did indeed lead to caffeine tolerance, decreasing the expected ergogenic effects. In this study, subjects were randomized to receive a low dose of caffeine (1.5-3 mg.kg) or a placebo for 28 days. In an aerobic performance test, the group that had regularly consumed caffeine had lost the performance benefit of caffeine supplementation (at a dose of 3mg/kg) that they had demonstrated at the start of the experiment, whilst the placebo group had not. This indicated that regular caffeine intakes of 1.5-3mg/kg (up to 210mg of caffeine for a 70kg individual) led to a blunting of the ergogenic effects of caffeine. 210mg of caffeine is often less than what you would find in a large filter coffee bought from high street coffee chains. Similar results have been found in other studies, although others have found no effect.
All of this prompted a new bit of research, published this month in the Journal of Applied Physiology. The title – Dispelling the myth that habitual caffeine consumption influences the performance response to acute caffeine supplementation – perhaps gives away the main findings of the paper, but I’ll summarize it nonetheless. Forty trained cyclists were split into three groups based on their regular daily caffeine intake. The low group consumed an average of 60mg of caffeine per day; the moderate group 143mg per day, and the high group 351mg per day. They all performed three simulated cycle time trials with either 6mg/kg caffeine, placebo, or control. Caffeine significantly improved performance, and there was no difference between the low, moderate or high habitual caffeine intake groups.
The Devil is in the Details
So where does the nuance come in? The main difference between last years and this most recent paper is in the dose of caffeine used. In last year’s paper, the habitual caffeine users were consuming up to 3mg/kg of caffeine per day, and then tested using 3mg/kg of caffeine. In other words, the amount of caffeine they took pre-exercise was the same as they regularly consumed. In the most recent paper, the high group consumed around 4mg/kg of caffeine on a daily basis, whilst they took 6mg/kg pre-exercise – so more caffeine pre-exercise compared to their habitual intake.
The conclusions from this are clear. Regular use of caffeine does not reduce the ergogenic effects of pre-exercise caffeine supplementation, provided the regular intake is less than the dose used before exercise. This provides some support for the idea that athletes can consume caffeine day-to-day, both pre-training and as part of their lifestyle, but they want to ensure that this daily intake is less than they take pre-race. Caffeine tends to be ergogenic at doses of between 3-9mg/kg, with no additional benefit seen with intakes above 9mg/kg. Some research also indicates that lower doses (1-2mg/kg) can also improve performance. What is clear is that the optimal dose is individual to each athlete; I found that doses above 3.5mg/kg caused me a lot of problems. As such, it would have been sensible for me to consume less than 3mg/kg on a daily basis, which I typically did.
The take-home message for athletes is that they can consume caffeine on a regular basis, but that it seems sensible to ensure that the daily intake is less than the amount they consume pre-competition. As regular use of caffeine might necessitate greater habitual caffeine intakes for the same effects, it is probably sensible for athletes to monitor their daily caffeine intake to ensure it doesn’t climb towards their pre-race dose. Doing so means that athletes can harness caffeine performance enhancing effects both in their day-to-day lives, and also during competitions.