Does Caffeine Really Boost Performance?

Written by Laura Isherwood

Caffeine & Performance

Many people will be aware that caffeine stimulates the brain and gives you that extra boost during the day, but are you aware of the effects caffeine can have on performance? Pre-workout shakes and gels are becoming more common these days, and more often than not, these products contain caffeine. But how does caffeine affect performance and what is the best way to consume it pre-workout?

What is Caffeine and How Does it Work?


Caffeine (1,3,7 trimethylxanthine) is the most widely used stimulant in the world. It is most known for its main mechanism of action, stimulating the central nervous system (CNS) and because of caffeine’s chemical structure, it can cross the blood-brain barrier and therefore decreases tiredness and increases arousal. Within sport, these two effects can have a great impact on performance. In addition, voluntary muscles (i.e. skeletal muscles which are controlled by an individual’s own will) are stimulated and regulated by the CNS; therefore caffeine can also have an effect on muscular strength and muscular fatigue.


Caffeine is also a common ingredient in several over-the-counter medicines as it blunts pain perception. In an exercise sense, this allows athletes to continue exercising at a higher intensity or for a longer period of time. Caffeine’s effects do not stop there either, they also alter substrate utilisation (the fuel in which you are predominantly using during exercise) and this can reduce fatigue in several sporting events.


So as you can see, caffeine works in loads of different ways, but what sort of performance benefits can you expect to see?

Performance Benefits


Caffeine has been shown to enhance endurance exercise (for example; a marathon or long-distance cycle), short-term high-intensity exercise (sprinting or HITT training), prolonged intermittent exercise (playing team sports) and even skill-based performance (such as passing in football or rugby).

Endurance Exercise


The aim of most endurance events is to complete the total distance in the quickest time possible, therefore the amount of fatigue a person experiences can ultimately determine performance.


During endurance exercise, the body predominantly uses the fuel glycogen (a type of sugar that you get from eating carbohydrates). However, once glycogen stores are depleted, you will feel tired and sluggish and may even experience a phenomenon called ‘hitting the wall’. Caffeine has been reported to encourage the body to use more fat as a fuel source, therefore sparing the glycogen and allowing you to conserve energy over long periods of time and reducing fatigue. A study published in the Journal of Sports Medicine and Physical Fitness [1] reported a 4-5% increase in performance during an hour long cycling time-trial. Many other improvements in endurance performance have also been found [2]. Therefore, any activities over an hour long (long distance running, cycling, skiing and swimming) all benefit greatly from caffeine consumption.

Short-Term High Intensity Exercise


Caffeine has also shown an increase in performance during strength and power activities, such as sprinting and weight-lifting. One study published in the Journal of Sports Medicine and Physical Fitness [3], reported that by consuming caffeine before bench pressing, people could complete 3 more repetitions than people who didn’t consume caffeine. These improvements have been linked to caffeine’s effects on the CNS, as the brain can stimulate more muscle fibres and reduce any feelings of pain, therefore allowing people to push through more repetitions during their workout or sprint that little bit faster.

Prolonged Intermittent Exercise


Team sports are extremely popular and again, caffeine seems to positively affect performance during them. In a recent study published in the Journal of Amino Acids [4], female players that ingested caffeine energy drink were able to increase their total distance, number of sprints and distance covered at higher speeds compared to players that didn’t ingest any. Again, these performance improvements have been linked to a number of caffeine’s mechanisms; however it is likely to be a result of glycogen sparing, as glycogen is needed to fuel sprints and fast-paced runs.

Possible Side Effects


Despite all the positive benefits of caffeine, users must be aware of the negative side effects that can occur from overuse.

Caffeine is a drug, and therefore people can become addicted. Withdrawal symptoms can occur if people drink more than 200 mg per day. Symptoms include headaches and cravings and can last for 2-9 days.

Some people often report a decrease in sleep quality following caffeine consumption; therefore it is important to get the right dose for you. Some people metabolise caffeine quicker than others and some people are just extremely sensitive to its effects.

How Should You Consume Caffeine?


There are several ways to consume caffeine and studies have shown that whether you drink coffee, take a pill or chew it in a piece of gum, makes no differences to overall performance. However some methods provide additional health benefits and some are far more practical.


Coffee (approximately 60-80 mg per cup) or Tea (40-80 mg per cup)


Probably the most common way to consume caffeine, however can take up to an hour before the caffeine takes effect as it has to pass through your digestion system.

Both Coffee and Tea are loaded with antioxidants which may help lessen any oxidative damage that occurs during your workout. Tea also contains EGCG (epigallocatechin gallate) which has been shown to have fat-burning properties.

coffee caffeine

Caffeine Capsules (100-200 mg per pill)


This is probably the most affordable way to consume caffeine pre-workout and is far more practical than having to drink a whole cup of coffee or tea. The 100-200mg dose however may be too much for some people and may cause headaches or shakes so start with lower doses and build up if you need to.


Energy Drinks (75-120 mg per can)


These may seem more convenient; however they are usually loaded with sugar (unless you opt for sugar-free versions) and are fairly expensive. They will also take up to an hour for the caffeine to take effect.


Pre-Workout Gels (30-100 mg per gel)


As previously states, the majority of pre-workout supplements will contain caffeine and pre-workout gels are one of the most practical and easy to use ways to get your caffeine boost. Not all gels contain caffeine so it is important to pay attention to the label. These gels usually work straight away and only need 15-30 minutes to take effect so are very useful to take just before making your way to the gym! I like to consume the Pulse Pre-Workout Gel (Berry Blast Flavour) just before my 20 minute walk to the gym as I find that when I’m ready to start exercising, the caffeine takes effect.


Caffeinated Chewing Gum (50-100 mg per piece)


The most recent method of caffeine delivery is by chewing caffeinated gum. This method works straight away as the caffeine is absorbed through your gums. Each piece only requires 10 minutes of chewing until the majority of the caffeine is released and absorbed.

These are incredibly practical and can also be taken during exercise (for example; at half time!). Some brands fail to mask the acrid taste of the caffeine, however I’ve found Blockhead Energy Gum ( works brilliantly and tastes good too!

When Should You Consume Caffeine?




Most people start to feel the effects of caffeine with as little as 20 mg (0.3 mg/kg of bodyweight). If you’ve never used caffeine before, start with a low dose and slowly work up accordingly.

The benefits of caffeine also appear to be optimal at around 200 mg (3 mg/kg of bodyweight) with higher doses not making any extra benefits. Higher doses are also more likely to give you some of the side effects previously explained.

However you decide to consume caffeine, be careful not to ingest more than the recommended daily allowance stated on the products.




Depending on your chosen method of supplementation, caffeine usually takes around 60-90 minutes to take effect. Therefore make sure you allow enough time before your training.

It is also important to state that caffeine has a relatively long half-life (about 6 hours), therefore if you ingest 200mg at 6pm, you will still have approximately 100mg in your system at midnight which may affect your sleep! So be careful and plan well!

Our articles should be used for informational and educational purposes only and are not intended to be taken as medical advice. If you’re concerned, consult a health professional before taking dietary supplements or introducing any major changes to your diet.

Casey Walker

Casey Walker

Experienced Sports Nutrition Technologist

Casey Walker is an experienced sports nutrition new product development technologist. He holds a Bachelor of Science in Sports and Exercise Science and a Master of Science in Sports Sciences and Physiology.

Casey’s scientific research area of expertise lies in the effects of dietary nitrates on sprint performance and exercise-induced muscle damage. He has also worked as a sports scientist for a medal-winning Paralympic track cyclist, with a goal of qualifying for the Rio 2016 Paralympics.

Find out more about Casey’s experience here.

In his spare time, Casey is a keen middle-distance runner with an interest in triathlon. He’s always looking out for the latest blends and supplements to improve his half-marathon time and recovery.

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