pre-run coffee in a mug

Caffeine for Marathons and Triathlon

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One of the easiest and most common (and accepted) performance enhancers for endurance races is caffeine. The energy and mental boost from caffeine can be a huge benefit in everything from a 5k to an Ironman distance triathlon.

So what is the best way to consume caffeine to improve your marathon or triathlon performance? We take a look at some of the science behind caffeine. Dive into what the easiest way to consume it is and when you should have some. And review some of the most popular running snacks and gels that contain caffeine to

How Much Caffeine is In Running Gels

The FDA says that caffeine is fine for you, with one study showing that “Evidence supported consumption of ≤400 mg/day in adults is not associated with overt, adverse effects.” That is the equivalent to around 4 cups of coffee or around 20 popular nutrition gels.

The actual impact on performance also seems to vary. Most studies seem to align around the suggestion of 3mg/kg of body mass. For 150 pound person that is roughly 200 mg of caffeine. To understand how to get this in your nutrition it’s important to figure out how much caffeine is in common products.

Note in the above chart is one of our favorite types of nutrition, especially when cycling. Tailwind is a drink mix that can be scooped and mixed with water. This makes it possible to get 300 calories and 100mg of caffeine in a single water bottle.

Is Caffeine Allowed in Marathons, Triathlons, and other Sports? Caffeine in World Anti-Doping Agency (WADA)

Saying that Caffeine is an approved substance is a broad statement and not entirely accurate. The history of caffeine as a preformance enhancers includes periods where it was banned from use in high level athletics, and that history is as recent as this century.

In 2003 the WADA updated guidelines to formally remove caffeine from their banned substance list. This meant that the Athens summer olympics were the first time in years that athletes could use caffeine for events. Even today, in 2025, caffeine is still on the monitoring list for WADA and the US Anti-Doping Agency.

Caffeine and the NCAA


For the collegiate world in the US the issue is even murkier. The NCAA produces a list of banned substances that includes “Stimulants” and lists caffeine as one such stimulant. Again, this is a potential over statement as Caffeine is allowed at some levels and ultimately the breach is determined by the concentration in a urine sample.

Finding out more leads to a web of scholarly journals that talk about the legality of caffeine in sport, caffeine concentration levels in athletic anti-doping tests, and a series of experiments that measured the impact of caffeine on various athletic feats including simple bench press and squats.

If all of this seems overly complicated for drinking a simple cup of coffee, it is! Consider that the NCAA’s own site notes that there is “NO COMPLETE LIST OF BANNED SUBSTANCES”. Again this is from the same site that then goes on to list Caffeine in a list of banned substances, but entirely ignoring that that only applies to certain levels.

It seems that the currently accepted limit by the NCAA is “15 micrograms per milliliter (ug/mL) of urine”. Of course urine concentrations will vary widely for any athletes. Hydration from other liquids and substances, body size, method of caffeine ingestion, genetics, and time since ingestion will all impact how a urine test measures.

This is a LOT of caffeine. To try to provide some perspective it is worth knowing that caffeine in extremely high doses can be a major issue. Some journals state that lethal doses of caffeine equate to “80 to 100 micrograms/ml”, so the limit is sport is 15-20% of a lethal concentration.

Most estimates seem to put the limit of caffeine to test above these levels to be around 500 mg of caffeine a few hours before perforamnce or a test. To put that into perspective, many of the gels and tablets listed above have 20-40mg.

So it would take ingesting around 12 standard energy gels with caffeine, pretty much all at once, in order to start triggering any anti-doping issue. Since most of those also include 100 calories it is unreasonable to think the average marathon runner or triathlete is going to take on 1200 calories of caffeinated energy gels all at once. More likely would be a concentrated caffeine product like a tablet.

Related Articles

Resources

  • NCAA 2024/2025 Policy “The definition of positive for the following substances is based on the potential for creating a pharmacologic advantage: for caffeine, if the concentration in urine exceeds 15 micrograms/ml“
  • World Anti-Doping Agency (Wada) 2025 Prohibited list “Bupropion, caffeine, nicotine, phenylephrine, phenylpropanolamine, pipradrol, and synephrine: These substances are included in the 2025 Monitoring Program and are not considered Prohibited Substances.“
  • FDA’s “How Much Caffeine is Too Much Caffeine?“
  • 2022 NIH Study study results that show “In summary, caffeine intake showed a meaningful ergogenic (enhancing physical performance) effect in increasing the time to exhaustion in running trials and improving performance in running time trials. Hence, caffeine may have utility as an ergogenic aid for endurance running events.“
  • Ironman “How to use Maurten gels in Training“, includes information for their on-course caffeine gels which contain 100mg of caffeine and 100 calories.

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