There is scientific evidence linking caffeine and athletic performance. Sports nutrition expert Renee McGregor explains how runners can maximise these benefits

In 2010 the International society of sports nutrition produced a position stand demonstrating a link between caffeine and athletic performance. There is scientific evidence to suggest it can benefit runners in a variety of ways. The most commonly documented use is to enhance performance but how it is administered will depend on the length of your run.

The other thing to take into consideration is finding out whether you are a responder or a non-responder to caffeine; if you are an individual who can drink a cup of coffee late at night and still sleep like a baby, then you are a non responder. In other words, caffeine has no effect on you or your nervous system. If the opposite is true, where you would be up all night tossing and turning, then that means you are a responder.

For longer events

In longer events, such as marathons or ultra distance, it is more useful to hold back on the caffeine until the latter stages of the race. Caffeine is known to help combat fatigue by having an action on the central nervous system, lowering the perception of effort, allowing you to keep going at the same pace for longer, or being able to increase your pace as you’re perceiving the effort to be less.

I usually suggest that individuals take caffeine in the last 1-2 hours of the training session or race to get the most benefit.

Weight loss?

The one area where there is little scientific evidence for the use of caffeine is when it comes to weight loss; several years ago there was some discussion, suggesting that consuming caffeine prior to exercise could increase the oxidation of fat for energy, aiding with weight loss.

However, study results have been varied and presently there is not sufficient conclusive evidence to make this claim.

Post-run cuppa

So we know it helps pre and during running but what about after? There does seem to be sufficient evidence to suggest that caffeine does have a place to play during recovery. A study published in The Journal of Applied Physiology 2008, demonstrated that if caffeine was provided as a recovery drink in conjunction with carbohydrate, it improved glycogen restoration by up to 66% after 4 hours post exercise, compared with just carbohydrate alone.

More recent studies have come to the same conclusion; practically, this is particularly useful for individuals who have less than 12 hours between training sessions. It promotes maximal glycogen resynthesis, ensuring that the individual has sufficient energy available for the subsequent session.

Don’t overdo it

So what about all the bad press that surrounds caffeine intake and dehydration? As mentioned earlier, there is no benefit in taking on more than the recommended amounts; in fact, excessive caffeine intake can have a negative effect on performance.


Intakes above 6mg/kg body mass can lead to an increased heart rate, feelings of nervousness, nausea and anxiety. Additionally, visual processing is also affected, which can potentially cause problems effecting fine motor skills and perception.

Similarly, caffeine has always been linked to increased diuresis, thus leading to dehydration. However, it seems that during exercise this does not occur: there doesn’t seem to be an increase in fluid losses even during heat stress. At rest, although caffeine does act as a mild diuretic, it seems that the fluid you consume in caffeinated drinks offsets this fluid loss.

It is now widely recognised that drinking caffeinated drinks in moderation doesn’t actually cause dehydration. For those of you who prefer not to take on caffeine but would still like the performance benefits, there are several alternatives such as wheatgrass and Matcha green tea. However, it is important to stress here that presently there is little scientific evidence supporting the use of these.

For shorter sessions

During short races up to a half marathon, or high intensity training sessions of up to 90 minutes, it is most useful to take caffeine 15-60 minutes before in order to get maximal effects; it can take up to 60 min for caffeine to reach peak concentration in the blood stream.

This can be taken in the form of a gel, cup of coffee or energy drink but it is important to get the right dose. Best results occur with intake of 3-5mg/Kg BW of caffeine. Studies have concluded that there are no enhanced effects by taking doses above this level.

So the average 60kg individual would need 180mg of caffeine and no more than 300mg; non-responders should work with the lower value and responders will probably gain some effects with the upper value.

This table provides information about average caffeine composition of common sports products and drinks: