The Caffeine Hit

News Written by Boris Clark

If there is one thing most endurance athletes (particularly cyclists) share, it is a love for coffee. The taste, smell, and warmth of a cup of coffee before, or after, a training session is lovely. But it is not just these factors that make us love coffee it is also what it contains, caffeine.

Caffeine makes us feel alert and energised, which is obviously beneficial from a psychological perspective, but did you know it can improve our performance from a physiological standpoint too.

Today I’ll be going through the mechanisms behind how caffeine can improve performance, how to take it, and how much to have.

The basics of caffeine metabolism

There are many ways caffeine works in our bodies, but one of the main ways is by having an effect on our brain.

Normally our brain creates something called adenosine and our brain has what are known as adenosine receptors. In a regular situation, the adenosine binds onto the adenosine receptors which makes us feel tired and slows down our nerve cell activity. As the day goes on we get more and more of this adenosine binding to adenosine receptors until we are very tired, and ultimately go to sleep at night.

That is a normal situation without caffeine, so what is caffeine’s roll in this?

To our brain, caffeine looks like adenosine. It is the same shape, so to speak, as what the adenosine receptor requires and therefore when we consume caffeine the caffeine can bind with these adenosine receptors instead of adenosine.

With this occurring we are not only avoiding the slowing down along neural pathways, by not having adenosine binding with adenosine receptors, but actually accelerating this neural cell activity. This is part of how caffeine acts as a stimulant. But both blocking adenosine, which slows down the nerve cell activity, and speeding it up through caffeine binding to these same receptors. It really is ‘hacking your brain’!

But wait, there’s more!

Caffeine also slows the rate at which we reabsorb dopamine, a chemical that makes us feel pleasure, which makes us feel good when we consume caffeine.

It also increases the release of norepinephrine (noradrenaline) and epinephrine (adrenaline) and also increases the length of time (Increases the half-life) of what is known as cyclic adenosine monophosphate (cAMP) by degrading phosphodiesterase. What does this string of barely pronounceable words mean? It means there is an increase in fatty acid release, meaning you have the potential to burn more fat. This certainly appears to be the case when at rest, though it is less clear if this really leads to greater fat burning during exercise. Caffeine does also appear to increase blood glucose, which would allow for greater/faster supply of glucose to working tissues for high energy bursts of activity, but may explain why there is some conflicting evidence regarding the fat-burning effects of caffeine when exercising, as this would result in greater carbohydrate usage. Caffeine does appear to increase exogenous carbohydrate oxidation specifically, however, which means the carbohydrate you consume while exercising from food, gels, or products such as UpShift SUSTAIN may be used to greater effect when caffeine has been consumed. Nonetheless, there is still a strong positive effect on the central nervous system from caffeine meaning we can send neural signals better which enhances our performance in other ways.

What type of activity does caffeine enhance?

To sum this section up very briefly when looking at all research into caffeine and sports performance almost all studies show a positive effect on performance, while those that do not show a positive effect tend to show no effect, though these are in the minority of studies. So in short, there is significant evidence that caffeine enhances all activity, and at the very least does not impair performance.

When we break things down it’s a little less clear cut than this but the same principle of not making performance worse applies. Looking at endurance activity there is overwhelming evidence that caffeine enhances performance, and this appears to hold true to sports/activities where quick reaction times or technical movements are involved. The evidence is a bit less clear cut for ‘anaerobic’ exercise, such as short sprints. However, again there is certainly no negative effect of caffeine on these activities and a likely positive effect. The same applies for more strength-based activities, such as weight lifting, where results from research appear to be mixed but certainly indicate either a positive effect, or no effect, from caffeine but certainly not a negative one.

Dosage and ingestion method

Everyone has their own caffeine sensitivity level. What this means is that the same amount of caffeine taken by one person could have a different effect to this same amount taken by another.

However, in general, doses of 3-9mg of caffeine per kg of body mass appear to be effective at enhancing performance, with doses of 3-6mg/kg proving to provide most of the benefit and doses above 6mg/kg not providing any further benefit, in fact, that is more likely to leave you feeling jittery!

Doses of less than 3mg/kg do appear to have a performance-enhancing effect but at this level higher doses to appear to be a bit more effective.

It is for this reason that UpShift EDGE is designed to be mixed to different strengths to fit each athlete's needs.

A popular way to get your caffeine in is coffee, however, the amount of caffeine can vary significantly depending on the bean used, the method of preparation, and how long it is prepared for. This means you really don’t know how much caffeine you are getting.

On that note, what is the best way to get caffeine in the system?

Caffeine does appear to be more beneficial when taken as caffeine, on it’s own or in a supplement, compared to when it is taken in something like a cup of coffee. However it has been shown that coffee consumption before or after caffeine consumption not from coffee (i.e. in a supplement like UpShift Edge) does not negate the performance enhancing benefits of the supplement, and the caffeine from the coffee, while not as beneficial as straight caffeine, does still enhance performance.

So have a serving of UpShift EDGE plus a cup of coffee and you’ll be set to fly!


It takes around 30 minutes to 1 hour for caffeine to reach peak levels in the blood. This means if you have an ultra short event such as a 5km run or a 10mile time trial there isn’t much point in taking caffeine as you go up to the start line, you’ll be finished before it kicks in!

The best strategy is therefore to time you caffeine intake to around 30-60 minutes before you start your event, or when you predict the hardest point of you event will be, if it is a longer event.

Caffeine has a half-life of around 4-5 hours but this can vary quite significantly depending on how you as an individual metabolise caffeine. What this means is that if you ingest one serving of UpShift EDGE (115mg caffeine), then 4-5 hours later you will still have around 55mg of caffeine in your system, though the majority of the benefit will have worn off. What this does indicate is that you are better having your caffeine on the early end of the scale rather than leaving it too late!

Some other effects of caffeine to be aware of

Caffeine is a great performance enhancer, but there are several factors to be aware of when it comes to caffeine consumption.


Caffeine is a known diuretic. This means it makes you urinate out more fluid. While this could increase the potential to dehydrate quicker, the diuretic effects of caffeine are not as pronounced as they were once thought to be. When you consume a product like UpShift EDGE you will be mixing it with water, or if you have coffee then you will obviously be consuming some fluid, so dehydration is less of a worry in this case, but is something to consider if you are taking caffeine in the form of caffeine tablets or similar.


Going back to the start of this blog, caffeine takes up the place of adenosine where adenosine receptors would normally sit. As adenosine makes us feel tired caffeine inhibits this effect by blocking adenosine. What this means in a practical sense is that while caffeine promotes alertness, it can also affect our ability to get to sleep. For this reason it is best taken earlier in the day, if possible. Obviously if you want to maximise performance for an evening event then this isn’t possible but it may mean it is worth trying a lower dose of caffeine for an event at this time, to get the performance enhancing effects of caffeine, without disrupting sleep too much.

It is also worth pointing out that just because you may be able to get to sleep after ingesting caffeine does not mean your sleep is of good quality. Even when you get to sleep your sleep can still be disturbed after caffeine consumption.


Unfortunately, like with most stimulants, our body adapts to continued caffeine consumption. Essentially the body works out something is wrong, it figures out the adenosine receptors can’t be getting filled with adenosine properly since we aren’t getting tired, and therefore creates more adenosine receptors. These of course get filled with adenosine making us tired.

One option is to take more caffeine, but this ends up in a cycle of more caffeine, more adenosine receptors, more caffeine, even more adenosine receptors and so on!

What this means is when you haven’t had caffeine in a while (e.g. when you wake up in the morning) you have way more adenosine receptors than before which can be filled, making you feel very tired until you have your morning caffeine, and once you have this caffeine it will restore you back to a ‘normal’ feeling, rather than an alert energised one. This is why we get a ‘withdrawal’ effect when we stop taking caffeine.

Obviously this means we need to be sensible with our caffeine consumption. Extreme caffeine intakes can have some adverse health effects, but assuming we aren’t talking supraphysiological dosages, it still means we need to ensure we aren’t continually having more and more caffeine.

So does this mean we should stop caffeine for a few days, or a week, before a big event?

The answer is ‘maybe’.

From a psychological perspective if we stop having caffeine for a while our brain will reduce the number of adenosine receptors, then when we have caffeine again we will feel a greater psychological alertness and boost.

But from a physiological standpoint, things are less clear cut. Some research shows stopping or reducing caffeine consumption for 7 days may allow a greater ergogenic effect from caffeine, while other research shows the level of habituation to caffeine doesn’t really matter in regards to the physical effects.

So the answer here really is it depends. From a psychological point of view, you will certainly feel a greater effect from caffeine if you stop having it for about a week before an event, but from a physical standpoint, it’s unclear. By stopping caffeine consumption you may get withdrawal effects which could cause irritability, muscle pain, and ironically even impair sleep despite having less caffeine!

Therefore it’s really up to you to experiment with this and see what works for you.


Caffeine can be greatly performance enhancing, particularly when taken in the right dosage and in its own form rather than as part of something like a cup of coffee. There are beneficial effects from both a psychological and physiological standpoint, and few drawbacks if used appropriately, but trial and error testing for individuals is probably the best way to work out what works best for you!


Until next time, happy training.

Boris Clark
Head of Performance
Metabolic Performance Solutions

PS. For those interested in learning more about performance optimisation head to my website

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