Caffeine and Exercise

Perhaps one of the world’s most common stimulants, this plant-based product is often used as an ergogenic aid to enhance endurance and performance of exercise.


Caffeine - found in coffee, tea, cocoa and chocolate, energy drinks and some medications - absorbs into the bloodstream rapidly and enters almost all of your bodily tissues meaning it can effect you in all areas from your brain to your nervous system to your heart.

In terms of exercise, the stimulating effect of caffeine means you are likely to be more alert, experience faster reaction times and perhaps even have a higher perception of pain meaning you can work harder and more effectively during your time at the gym.

When it comes to endurance, caffeine is found to slow down the depletion of glycogen (the body‘s preferred source of energy) and instead encourage the breakdown of fat, also known as lipolysis, to provide the fuel required to plough through. With a longer lasting supply of glycogen stores the body is able to perform for extended periods without fatigue. Those that benefit most from caffeine in this instance are endurance runners or cyclists, or those training for more than an hour. There is some evidence to suggest caffeine consumption prior to exercise is beneficial to the average gym-goer , but when your workout is completed in 45-60 minutes caffeine is not likely to be as effective as a pre-workout.

To maintain peak performance it's important to keep well hydrated. If you’re working sufficiently hard during your workout the need to take on more fluids is ever more important. Without adequate hydration it becomes more difficult for your heart to circulate blood around the body which can lead to muscle cramps, dizziness and fatigue.

Whilst caffeine is labelled as a diuretic meaning it can make you pee more and thus leave you more susceptible to dehydration, evidence suggests that, when consumed in moderate amounts (no more than 400-500mg) there will be no detrimental aefect on hydration levels - so no need to worry about that one!

To get the best results in using caffeine as an erogenic aid I would suggest limiting your intake generally and consuming it 1-2 hours prior to your gym sessions.

So what is the recommended daily intake of caffeine and how much is in what I eat and drink?

The average adult is currently advised to consume no more than 400mg caffeine per day. This recommendation is halved for pregnant women - so no more than 200mg per day as it may impact the growth of your baby.

1 mug filter coffee - 140mg
1 mug instant coffee - 100mg
1 can (250ml) Red Bull energy drink - 80mg
1 mug of tea - 75mg
50g dark chocolate - 50mg
1 can of Coca Cola - 40mg
50g milk chocolate-  25mg

Looking beyond caffeine and exercise, and focussing on the two main sources of caffeine - tea and coffee - it ought to be noted that there are other benefits to your daily cuppa...

For example, two cups of tea per day could help improve cardiovascular (heart) health as the catechins tea contains are said to be cardio-protective. Additionally, some studies have linked moderate consumption of coffee to boosting memory function as we age and even to the lowering the risk of inflammatory diseases, such as Type 2 diabetes, due to the presence of antioxidant polyphenols.

However, don't forget that as a stimulant, caffeine consumption does present some cons. Too much caffeine can lead to irritability, anxiousness, headaches and disrupted sleep patterns and excessive amounts can alter hormonal balance and deplete mineral stores within our body.

Finally, caffeine can be addictive. Over time excessive consumption means you become more accustomed to the benefits offered and thus require greater amounts to feel the same ‘buzz’ and alertness you felt when you first started consuming it.

The key - as in almost all things - is moderation.