How to Use Caffeine for Endurance Performance

One of the ergogenic aids I get the most questions about is caffeine. Many athletes swear by their daily fix, but a few avoid it at all costs. Some might stick to tea or coffee, while others prefer caffeinated gels or a combination of both. In this post, we’ll examine what caffeine does in your body and brain, why you might have good or bad reactions to it, and how to use it to power your training and racing.

The three responses to caffeine

How or if you respond to caffeine might seem totally random, but research shows that it’s actually hardwired into your genetics. A study published in Medicine & Science in Sports & Exercise stated that a variation in the CYP1A2 gene that regulates caffeine was likely responsible for three different outcomes in cyclists who consumed it. One group finished a time trial faster with two and four mgs per kilo of bodyweight, a second experienced no effect, and a third had a decrease in performance. The takeaway? Keep using caffeine if it helps you or you enjoy the taste of tea or coffee, but don’t force it if it doesn’t seem to do anything or makes you feel worse.

The physical & mental benefits of caffeine

Caffeine is a central nervous system stimulant that blocks tiredness-causing adenosine from binding to receptors in your brain, while stimulating the release of adrenaline, noradrenaline, and catecholamines, which include the so-called “happy hormone” dopamine. The International Olympic Committee (IOC) includes caffeine on a very short list of supplements that it states are backed by “good evidence of benefits,” along with creatine monohydrate, nitrate, sodium bicarbonate, and beta-alanine. 

Studies have shown that caffeine helps increase time to exhaustion, improve speed, and boost power output. The ways it does this include decreasing pain and the perception of effort and fatigue, which may help you push past your usual limit and keep going harder for longer. According to the International Society of Sports Nutrition, caffeine also has cognitive benefits, including increased vigilance, attention, and overall acuity, suggesting that it helps you maintain focus on your performance.

Caffeine right before running

A Journal of Strength and Conditioning Research review of previous studies discovered that the impact of caffeine on endurance performance varies greatly, from a 0.3 percent decrease to a 17.3 percent increase. In addition to the genetic factor, they explained that caffeine consumption habits, timing, dose, and method of ingestion can all contribute to this variable impact. While your response is individualized, caffeine seems to peak in your system around 60 minutes after consumption, with the beneficial effects lasting around 1 hour. With this in mind, it’s important to consider when you’re going to use it with optimal timing for training and racing. 

Before you head out the door to run, it’s best to stick to your usual daily caffeine schedule, as your body and brain will get bamboozled if you’re used to a morning and/or afternoon cup of coffee or tea and suddenly avoid it. The same goes for race day. Conversely, if you don’t normally consume caffeine before a run, it’s not best to try it out for the first time prior to a long or hard session, or right before you show up to the start line. Nor should you jack up your caffeine consumption in the belief that if some is good, more must be better, as studies show that beyond a certain point there’s no extra benefit and you might actually start to develop jitters, tummy troubles, and other unpleasant side effects. 

Consuming caffeine during training & racing

In the IOC position paper, the authors wrote that “Caffeine consumption during activity should be considered concurrent with carbohydrate (CHO) intake for improved efficacy.” This is where caffeinated gels can come in handy. Again, there’s no one-size-fits-all prescription here, but what I’ve found to be effective for marathons and other longer races is to alternate caffeinated and non-caffeinated products. Three to six milligrams per kilogram of bodyweight before and during training and racing is the amount many studies have found increases endurance performance by 2-4%. 

This range is really broad, but 200 mg is a sweet spot for many runners. That’s two cups of coffee or two stronger gels, like Maurten Gel 100 Caf 100. Good products like this that have been vetted by NSF Certified for Sport or Informed Sport accurately list the caffeine amount, making your trial-and-error process easier. As with any supplement, start with a low dose and carefully build up as needed. 

Remember that it takes an hour for caffeine to fully kick in and that a lot of runners need it most in the second half of a race. So, if you were running a three-hour marathon and wanted to keep pushing hard in the last 10K, take a caffeinated gel at 60 minutes. Or if you’re on pace for four hours, caffeine at the one- and two-hour marks might help you finish strong. As I advised for your overall nutrition/hydration plan in a previous post, practice your caffeine strategy on long runs so that you iron out any kinks and dial in timing and total dosage to tap into the performance benefits on race day.

1. Nanci Guest et al, “Caffeine, CYP1A2 Genotype, and Endurance Performance in Athletes,” Medicine & Science in Sports & Exercise, August 2018, available online at 2. Ronald J Maughan et al, “IOC Consensus Statement: Dietary Supplements and the High-Performance Athlete,” British Journal of Sports Medicine, April 2018, available online at 3. Nanci Guest et al, “International Society of Sports Nutrition Position Stand: Caffeine and Exercise Performance,” Journal of the International Society of Sports Nutrition, January 2021, available online at 4. Matthew S Ganio et al, “Effect of Caffeine on Sport-Specific Endurance Performance: A Systematic Review,” Journal of Strength and Conditioning Research, January 2019, available online at

Disclaimer: The content in our blog articles provides generalized nutrition guidance. The information above may not apply to everyone. For personalized recommendations, please reach out to your sports dietitian. Individuals who may chose to implement nutrition changes agree that Featherstone Nutrition is not responsible for any injury, damage or loss related to those changes or participation.