Can we rely on the caffeine content in coffee for performance?

Caffeine seems to be every endurance athletes' favourite 'legal superpower' - but is that pre-race Flat White actually providing the dose you think it is? 

From busy workdays to big-race mornings, caffeine quietly powers most of the population, yet its true performance potential - and pitfalls - are often misunderstood. We sip coffee, slam gels and knock back energy drinks, assuming they all deliver the same boost, when in reality, the dose (and therefore the benefit) can vary wildly from cup to cup. 

In this article accredited Sports Dietitian Cushla Holdaway (below) unpacks what caffeine really does for your brain and muscles, and whether relying on coffee alone is smart strategy, or a risky roll of the dice on race day.

Caffeine: A popular legal performance enhancer since 2004

Caffeine is one of the most well researched supplements in the world and a very common psychoactive agent in our daily lives consumed by ~90% of adults. 

Caffeine is commonly consumed in coffee, tea, energy drinks, and some sports supplements (e.g. energy gels, sports drinks, energy chews, energy bars).

In 2004, Caffeine was withdrawn from the WADA (World Anti-Doping Agency) Prohibited List, allowing athletes to utilise this for performance without fear of being penalised.

Caffeine has numerous impacts on the body, both positive and negative depending on individual tolerance.

The main positive impact is due to its effect on the central nervous system, by-election reducing the perception of effort and fatigue, alongside various roles within the circulatory system and skeletal muscle.

Ultimately, when it comes to sport, caffeine helps us push harder for longer with less perceived effort. Like most topics within nutrition, there is a bell-shaped curve with too much caffeine potentially having unpleasant side effects including elevated heart rate, reduced fine motor control, and impaired sleep. Excess single doses >500mg at a time are generally discouraged. 

The ideal dosage of caffeine is 3-6mg/kg bodyweight prior to an effort (210 – 420mg for a 70kg athlete) and usually peaks in the bloodstream 45-90-minutes following ingestion, so keep this in mind prior to training and races! 

Caffeine has a half-life of six-to-eight hours, meaning half the caffeine you have consumed will still be in your system six-to-eight hours later… an important consideration for sleep hygiene!

How much caffeine is in a cup of coffee? 

With caffeine dosage in mind, how can we be sure how much we are consuming from coffee? 

A 2024 Polish study (Wierzejska RE. et al.,) took samples of 208 coffees between 2021 and 2023 including espresso, lattes, cappuccino and Americanos from various outlets (Starbucks, Costa, McCafé and fuel stations). From all these samples, the coffees averaged 82mg of caffeine with a massive range from a mere 13mg to a massive 310mg dose!

Americanos generally had the most caffeine, while homemade ground coffee had the least.

Other findings included Arabica beans having less caffeine compared to Robusta beans, and caffeine content varied up to seven times within the same brand of cappuccino.

Although coffee can be a very enjoyable and easy way to consume caffeine habitually, it can be unpredictable when it comes to caffeine intake.

The key takeaway is, if you are wanting to be precise with caffeine dosage around key races, you are safer to take a supplement that contains a standardised dose.

Caffeine content of common foods/sports supplements:

·  Cup of tea ~10 – 50mg

·  375ml Coca-Cola 50mg

·  250mL can of Red Bull 80mg

·  No-Doz capsule 100mg

·  Sports energy gels ~30-100mg

·  Pre-workout supplements ~150-300mg per serve

·  Cup of barista made coffee (highly variable) ~13-300mg

 References

·  Evans J, Richards JR, Basttisti AS. Caffeine. [Updated May 29 2024]. In: StatPearls [internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK519490/

·  Goldstein, E.R., Ziegenfuss, T., Kalman, D. et al. International society of sports nutrition position stand: caffeine and performance. J Int Soc Sports Nutr 7, 5 (2010). Available from: https://doi.org/10.1186/1550-2783-7-5

·  McLellan, T., J. Caldwell, and H. Lieberman. (2016). A review of caffeine’s effects on cognitive function, physical and occupational performance. Neuroscience and Biobehavioral Reviews, 71, 294-312. Available from: https://pubmed.ncbi.nlm.nih.gov/27612937/

·  Wierzejska RE, Gielecińska I. Evaluation of the Caffeine Content in Servings of Popular Coffees in Terms of Its Safe Intake-Can We Drink 3-5 Cups of Coffee per Day, as Experts Advise? Nutrients. 2024 Jul 23;16(15):2385. doi: 10.3390/nu16152385. PMID: 39125266; PMCID: PMC11314177.

About Cushla

Cushla is an Accredited Sports Dietitian based in Mid-Canterbury, specialising in nutrition for endurance athletes from beginners to elites.

With a BSc in Human Nutrition and a Master of Dietetics (dist), she offers personalised consultations across New Zealand, both in-person and online. Cushla is also the dietitian for the New Zealand Defence Force (Burnham), runs online education courses, and hosts a podcast ‘Nourish Your Potential.’

Passionate about running and evidence-based nutrition, she helps athletes optimise performance and health through practical, realistic, and individualised advice.

Website:  www.holdawaydietitian.com 

Instagram: @cushlaholdaway_dietitian