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The relationship between sports performance and caffeine intake.

Updated: Apr 22, 2021

In this blog we will be discussing caffeine as a performance enhancing supplement and its effects on health and wellbeing of its users. Is it all it’s hyped up to be or can it have detrimental effects on our overall health? Caffeine is a widely used stimulant, found in numerous day to day products, and it consumed by over 85% of adults across the world (Wilson, 2018). Countries like Japan (260 mg/day), Finland and Norway amongst others have higher intakes of caffeine as part of their daily consumption when compared to the average American (186 mg/day). Research about the ergogenic properties dates back to 1893 (Perkins and Williams). Bans for highly concentrated caffeine products in athletic completion were reviewed by science as far back as 1939. However, despite caffeine being a vastly researched subject, the effects on performance and safety of consumption are still widely discussed and reviewed.

Caffeine is found in various day to day foods and beverages such as tea, coffee, soft drinks, chocolate as well as medications. Other forms of caffeine include pre-workout drinks, energy shots and chewing gum. The amount of caffeine in each of these and the rate of absorption varies depending on the method of consumption. One of the benefits of caffeine, is that it is a widely available and affordable, legal ergogenic aid. However, one needs to analyse whether caffeine intake does really enhance performance and whether there are any health risks associated with the intake required to enhance performance if any.

Coffee is a cheap and easy way of consuming caffeine however it is difficult to quantify the quantity of caffeine consumed in every cup of coffee. The dose of caffeine per cup varies on the type of coffee, the exact coffee bean, roast type, and preparation method. For example a cup of black tea (~47 mg) yields in a lot less caffeine than a cup of strong blend cup of filter coffee (~100 mg) (Table 1). Studies by Graham et al, show that when consumed as coffee it was not as effective as when it is consumed as a capsule. Other studies by Hodgson et al show that the source doesn’t affect performance provided the right does is consumed. Caffeine intake from sports drinks or energy shots is somewhat more quantifiable than when consumed in a cup of coffee as the quantity of caffeine in a brewed coffee can vary per cup.

The speed at which blood caffeine levels increase in response to drinking caffeine (tea, coffee, energy drinks) doesn’t really vary between sources. The differences in absorption would be negligible but could be likely to the differences in pH, volume and concentration of fluid consumed. For a quick absorption rate, chewing caffeinated gym would be a better option as it is absorbed through the oral mucosa resulting in quicker increase in blood caffeine levels following consumption (30-50% faster). Different individuals have different performance outcomes and absorption rates, so these are additional factors to consider when looking at dosage and timing of caffeine intake.

The minimum recommended does is 3 mg/kg of bodyweight (an average cup of coffee) helps with wakefulness and alertness, however for performance enhancing benefits higher doses are required. The optimal dosage is around 5-6 mg/kg of bodyweight, which for someone weighing in at 100 kg would total 600 mg of caffeine. This is around 6 cups of filter coffee in one go! Most pre workout drinks contain anywhere between 150-350 mg of caffeine, so the higher your body weight, the higher the quantity required. Research also shows that consuming doses above 6 mg/kg do not produce any performance enhancing effects but can have negative side effects such as tremors, dizziness, vomiting.

The timing of caffeine intake might vary for individuals, depending on their absorption rate, however around 99% of orally ingested caffeine is absorbed within 45 minutes of ingestion. Within the first 15 minutes of oral ingestion, substantial increases in blood caffeine concentration are observed, typically reaching peak absorption values within 30-60 minutes. Longer timescales of up to 2 hours have also been observed, and this could be dependant on factors such as gastric emptying and the presence of other nutrients in the system that can affect a delayed rate of caffeine absorption in the blood. Caffeine clears the bloodstream in around 3-6 hours, however in certain cases it can be as low as 2 hours or as high as 12 hours. Caffeine intake can hinder sleep so the timing of caffeine intake on an evening might be a detrimental factor if it is negatively affecting sleep patterns. Due to its fairly long half life, it is recommended to limit caffeine intake on late afternoons and evenings. Persons suffering from sleep apnea or prone to sleep difficulties should avoid high consumption of caffeine or avoid it completely if it is detrimental to their overall wellbeing.

Alternative sources for more endurance based sports are energy gels containing caffeine. These are easy to carry around, when running or cycling and are more practical to consume on long distance runs, cycles or races. Over the years, caffeine intake has been associated with endurance sports athletes, however popularity has grown within team sports that require long bouts of prolonged energy such as rugby and football. A great deal of research covers the effects of caffeine on performance for endurance athletes, but there is less information about the effects of caffeine on strength training performance.

Team sports such as rugby require ergogenic aids that provide enhanced performance for longer durations but also for strength and power output. Using caffeine alone will potentially not be enough to produce the required increase in performance outcomes for high impact sports such as rugby. It is common practice to use caffeine alongside other ergogenic aids such as nitrous oxide or creatine for enhanced performance gains. Most pre workouts already contain a combination of these ingredients, whilst providing additional hydration (mainly if the pre workout is mixed with water) which will be beneficial in preventing or reducing cramps that might be linked to lack of hydration following an intake of a high dose of caffeine. One of the reasons for dehydration could be the increased urine flow when consuming caffeine, however when caffeine is consumed in liquid form such as a cup of coffee or in a pre workout drink then this dehydration effect is minimal. If caffeine intake is in the form of a shot or gum then it would be beneficial to increase fluid intake to maintain optimal hydration levels required for the sport. Additional intake of supplements such as electrolytes is also beneficial alongside caffeine supplementation.

Another point to reflect on is whether regular caffeine intake can hinder performance over time, if the athlete gets used to consuming caffeine on a daily basis, the body adapts to this state and might require higher doses to increase performance. However, as mentioned earlier, if the optimal dose of caffeine for improved performance is around 5-6mg/kg then for a 100kg athlete requiring 500-600mg of caffeine to enhance performance. If the athlete is regularly consuming >300mg of caffeine on a daily basis in regular drinks such as tea or coffee (say 3 cups of filter coffee) then that will only be increasing the intake pre training by 300mg so as not to exceed the recommended doses, as this will not have an increased effect on performance. A dip in performance can be observed over time when athletes are in an adaptive state. A way to offset this is to cycle caffeine intake to reduce the dependancy on this supplement and potentially only taking caffeine on training or game days to achieve the maximum benefit. Stopping caffeine intake suddenly can have adverse side effects mainly in the first 24-48 hours such as headaches or drowsiness, as well as a potential negative effect on training performance due to the reduced stimulant intake. If an athlete is feeling less energetic and alert, this is likely to have a negative effect on their performance in the gym or on the pitch, so this is something to consider when looking at the timing of reducing or eliminating caffeine intake. It would be more ideal to cycle in the off season or during a recovery period or de-load phase where lower performance outputs are required and the athlete can tolerate or be prepared for any withdrawal symptoms.

One concern regarding caffeine intake is whether there are any health risks associated to regular caffeine intake. Apart from the above mentioned dips in performance, provided one stays within the recommended dose for their body mass then it is deemed as a safe supplement which enhances performance. Regular consumption within this range or tea and coffee are associated with neutral to positive effects on a wide range of health outcomes. All in all, we can conclude that caffeine intake does have a positive effect on performance output so is a beneficial training aid for elite and recreational athletes to increase their performance output. The benefits are more apparent for endurance events rather than for strength training, but it would still be a suitable supplement that’s affordable and easily available. Ensuring the right quantity is consuming and managing the timing of intake plays an important role to maximise overall benefits.


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Lucas Guimarães-Ferreira, Eric T. Trexler, Daniel A. Jaffe, Jason M. Cholewa, 19 - Role of Caffeine in Sports Nutrition, Editor(s): Debasis Bagchi, Sustained Energy for Enhanced Human Functions and Activity, Academic Press, 2017.

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Table 1: Source: https://cspinet.org/eating-healthyingredients-of-concern/caffeine-chart

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