caffeine for ultrarunners

New Science on Caffeine for Endurance Athletes and Ultrarunners


By Jason Koop,
Head Coach of CTS Ultrarunning

In the very early part of my coaching career, far before I was working with elite athletes, caffeine was considered a controlled substance per the World Anti-Doping Agency (WADA). Meaning, if an athlete had too much caffeine in his or her system, they would be subject to a doping sanction, similar to athletes getting busted for EPO and testosterone do today. At that time, the threshold for a positive test was set rather high, equivalent to drinking about 10 espressos over a few hours for a normal sized male. Yet, despite this unusually high threshold (which was put in place as to not penalize social coffee consumption), several athletes during that era served caffeine-derived doping sanctions anyways, which gives an entirely new meaning to the phrase, ‘all hopped up on something’. WADA eventually removed caffeine from the banned list in 2004, giving Starbucks permission to fuel Olympic hopefuls at will.

All jest aside, the real point here is that caffeine is a powerful ergogenic aid. Once a banned substance, it is now one that has been studied copiously, particularly since it was legalized in Olympic sport. We know how caffeine affects endurance, speed, stamina and cognition, what the mechanisms of action are, and even a fair amount about what causes individual variability. We know a tremendous amount about effective dosing and no, 10 espressos is not the optimal dose (far from it, actually). It’s one of the few drugs that we can safely and confidently prescribe interventions with and have more than a reasonable amount of certainty that it will improve performance. Keep that in mind the next time you are attempting to haphazardly chase down performance gains with an amino acid supplement derived from wasp, the latest ketone ester, or even some cordyceps sinensis mushrooms.

A new behemoth of a review paper and position stand in the Journal of the International Society of Sports Nutrition, elucidates what we currently know about caffeine consumption and exercise performance. It’s a heap to take in at 37 pages, over 400 citations and well over several cups worth of coffee to churn through. It’s open access, so please feel free to read for yourself from the link above.

How much benefit from caffeine?

One of the great things about caffeine supplementation in sport is that the benefits apply across a wide range of endurance sports and athletes. Cyclists, runners, cross country skiers and triathletes all enjoy performance benefits from caffeine. They also do so at a variety of intensity domains, from short time trials to longer time-to-exhaustion tests and interval protocols alike. Additionally, caffeine’s ergogenic effects seem to know no boundaries of age, sex or aerobic prowess (VO2max).

On average, endurance athletes enjoy about a 2-4% performance improvement, depending on the type of test and with moderate doses of caffeine (more on that below). This not only means that you can race faster, but also that you can maintain higher intensities for longer during workouts, potentially leading to bigger adaptations.

Caffeine Dose and Timing

As a byproduct of the many research studies performed on caffeine, we know a lot about how different dosages affect performance. As it turns out, there is a sweet spot between 3-6 mg/kg. Less than that, and the ergogenic benefits are not as robust. Consume more than that range and there are no additional benefits. Easy math will tell you how many milligrams the optimal dose will be for your body mass, but it’s a more difficult proposition to determine how much caffeine is in your coffee (if that is your chosen source of caffeine). We’ve known for several years now that the caffeine content even in the same beverage from different store can vary as much as nine fold (for purposes of simplicity, I am going to use caffeine equivalents of 95 mg of caffeine for an 8 ounce cup of coffee and 64 mg of caffeine for a shot of espresso in this article).

Using myself as the prototypical 75 kg (165 lbs) example, this would mean consuming anywhere between 2.5 and 5 cups of coffee or a similar amount from sports nutrition products to reap the benefits.

In terms of timing, things get a bit trickier depending on the exact situation you are in. Most research studies use a standardized consumption window of one hour before exercise in an attempt to time the effort to coincide with peak plasma caffeine concentrations (which happens anywhere from 30-120 minutes depending on the person). This timeframe works fine if you are doing a short workout or sipping on some espresso before your morning intervals. In this situation, you can have your dose of caffeine, then get your gear ready, head out the door, warm up and have your caffeine pump primed to hit this window optimally. But for ultramarathon athletes that routinely go on runs lasting longer than a few hours, I recommend waiting until the second half of the run to start consuming caffeine and stop the caffeine consumption at least one hour before the end of the run. Caffeine has been demonstrated to have particularly beneficial effects for athletes under fatigue and engrossed in long duration exercise.

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Another practical issue in regard to timing is when you consume caffeine in relation to your bedtime. If you generally run in the evening or afternoon, any workout benefits achieved from caffeine consumption can easily be erased by a night of restless and or reduced sleep. Best skip a pre-workout shot of espresso or caffeinated gel in these situations.

Interindividual variability

Despite some of these universal recommendations, like any nutritional intervention, there are still athletes who don’t respond well to caffeine. Some research has pointed out that so called genetic ‘slow metabolizers’ could be poor candidates to caffeine interventions. While some studies show that caffeine impairs performance in slow metabolizers, others show no difference or even the exact opposite, that caffeine’s benefits only show up in people who are slow metabolizers.

If you have had any sort of genetic testing from a company like 23 and me or Helix, chances are you can find out if you are a genetic ‘fast’ or ‘slow’ metabolizer (the primary gene to look for is the CYP1A2 gene). However even armed with this information, you would be best served to test out different caffeine doses in training with different timing and see how you react.

Caffeine abstinence

Since caffeine’s legislation by WADA, much has been made about the need (or lack thereof) to abstain from the drug in the days leading up to the race in order to maximize benefits. Race week coffee abstention, which left many endurance athletes irritable, grumpy and downright miserable to be around, has fortunately been found to be unnecessary and even problematic. While many athletes still adhere to this old adage in an effort to feel ‘race ready’, there’s really no need to. Benefits are maintained regardless of if you continue to consume caffeine or not in the days leading up to an event. Given the potential and well documented side effects of caffeine withdrawal, feel free to keep your normal caffeine and coffee routine leading up to a race.

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Caffeine and alertness

One of caffeine’s most potent benefits relates to alertness and cognition in sleep deprived states. If you have even done an overnight ultra or 200 miler, you have had the experience of not being able to perform simple tasks after a night of no sleep. Fortunately, our military has had a long and storied history of subjecting soldiers to sleep deprived training scenarios and then introducing interventions to help them perform better on the field of battle. As it turns out, caffeine is great in these scenarios; soldiers show improved decision making, marksmanship, and reaction time. The extrapolation of this research for ultrarunners is that if you have an overnight ultra, caffeine should certainly be a part of your race plan. However, caution should be used, as too much caffeine too early can cause adverse side effects. Therefore, I have developed the following guidelines I use for athletes when considering caffeine.

An Ultrarunner’s Action Plan to See Benefits From Caffeine

  1. Test different amounts of caffeine in training to see how your body responds. Consider incorporating genetic testing to add context to what you’re seeing from trial and error.
  2. If using caffeine to improve performance in 50km or 50-miler, consume up to 50mg/hr in the second half of your event based on what has worked in training.
  3. If using caffeine to improve alertness during a 100-miler:
    1. Avoid caffeinated products until performance is significantly threatened by feeling tired (not fatigued, but sleepy).
    2. Supplement with the amount shown to work in training, up to about 100mg/hr. Remember that more is not necessarily better.

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Comments 7

  1. Pingback: 25 Tips on How to Stay Motivated to Workout - GenZ Outdoor

  2. Great article. I used to skip coffee a week or even two before big races (100k or 100M) and drink coffee when feeling tired during the race. I suppose the stronger “kick” was a bit of a placebo effect from coffee deprivation, but I’m happy to know that this is no longer necessary!

  3. Great article, thanks!

    However, could you please elaborate on the adverse effects of caffeine use. I have read a new study out that was a lab test with several athletes in perfect physical condition with excellent VO2. They were all given (x)mg of caffeine at intervals and also were working at a specific intensity on the bike. The results were very interesting with blood coagulation. Blood clots(thrombosis)(DVT) promotion.

  4. The article states the many positives of Caffeine on performance!
    What about the negatives?
    I was a keen triathlete who frequently used quite moderate dozes of caffeine to improve performance.
    I have now suffered from atrial fibrillation and reading an article published by Cleveland Clinic it would seem that doses of caffeine can lead to heart arrhythmia.
    What are your thoughts?

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