Caffeine and endurance is one of the most studied topics in sports nutrition. For many endurance athletes, a planned caffeine intake can, in some cases, help make the final part of a workout or race feel more manageable.
In this guide, you’ll get an overall overview of what research typically points to, and how you can translate it into a concrete strategy for training and competitions, so you use caffeine in a way that fits you and your needs.
What the research shows about caffeine and endurance
A number of studies and meta-analyses suggest that caffeine can, for many people, contribute to a small improvement in endurance performance—often on the order of a few percent—in sports such as running, cycling, triathlon, and rowing. How much it matters in practice depends, among other things, on distance, intensity, and individual response.
Typically, you see that:
- Doses around 3–6 mg of caffeine per kg of body weight are the most studied
- Caffeine is typically used in connection with aerobic endurance, where you work hard for a longer time
- The effect can often be linked to a lower perceived fatigue, improved focus, and the ability to maintain pace toward the end of a session or a race
The effect is also individual. Genetics, sleep, diet, caffeine habits, and gastrointestinal tolerance mean that some experience a more noticeable effect than others.
If you want to work purposefully with caffeine in your own training, it can be beneficial to get an overview of PurePower’s caffeine products for training and competition, so you can choose the form and amount that suit your body and your goals.
How to dose and time caffeine in practice
When research examines caffeine and performance, some common denominators recur, which you can use as guideposts in your own planning.
- Amount: Often 3–6 mg of caffeine per kg of body weight
- Examples: 50 kg corresponds to approximately 150–300 mg, 70 kg approximately 210–420 mg
- Timing: Intake about 30–60 minutes before the start, when caffeine typically peaks in the blood
- Duration: The effect can extend for about 3–5 hours and gradually declines
In a Danish context, it is also important to stay within the general recommendations of about 400 mg of caffeine per day for adults and about 300 mg for pregnant women, regardless of whether the caffeine comes from coffee, energy drinks, chocolate, or sports nutrition.
A simple model for a marathon or long cycling races could, for example, be:
- A moderate dose before the start, for example 2–3 mg/kg
- Smaller amounts along the way via energy gels with caffeine or caffeine-containing chews, when you want support for focus and perceived exertion
What happens in the body when you use caffeine
Caffeine primarily affects the central nervous system, and this is especially relevant for endurance athletes because it can be related to how fatigue and exertion are experienced along the way.
- Blocking adenosine: Adenosine is a signaling substance that, among other things, is associated with fatigue, and caffeine can block some of its receptors, which for some may contribute to a less pronounced feeling of fatigue
- Perceived exertion: Many describe that the same pace can feel easier with caffeine, so in some cases you can sustain the intensity for longer
- Focus and decisions: On the bike, in running shoes, or on the track, increased attention in some can make it easier to follow tactics, fueling plan, and small decisions
In practice, this means that caffeine can often be relevant:
- On long training sessions over 90 minutes
- In competitions where you need to hold a steady pace for a long time
- In the final stretch, where fatigue typically plays a bigger role mentally and physically
How to choose the right caffeine form
Research does not suggest that caffeine in capsules is inherently more effective than caffeine from coffee or sports nutrition. What usually matters is the total amount, the timing, and how your stomach reacts.
Many endurance athletes choose forms that fit naturally into their fueling plan:
- Capsules: A precise dose without extra carbohydrates, which can be easy to use to hit your planned dose before the start
- Gels with caffeine: Combine carbohydrate and caffeine in one solution, so you get carbohydrate for your fueling plan and caffeine as part of your strategy
- Chews and chewable products: A solid “gel” in gummy form, which for some can be practical and easier to consume along the way
- Electrolytes with caffeine: Provide fluid and salts as well as caffeine, which for some can be relevant in heat or during prolonged sweating
- Pre workout shots: Typically used before hard training sessions or shorter competitions, where you want to take caffeine as part of your preparation
Your choice largely comes down to taste, stomach, and logistics. No matter which form you choose, it’s important that you test it in training and don’t wait to try it for the first time at an important competition.
How caffeine works together with energy and fluid
Caffeine can be included as a supplement, but it cannot replace either carbohydrates or fluid. For many, caffeine works best when it is part of an overall plan for energy and fluid.
A simple checklist for long sessions and competitions can look like this:
- Carbohydrates: Have a plan for how many grams of carbohydrate you want to consume per hour, for example 40–70 g via gels, chews, or sports drink
- Fluid and electrolytes: Drink to thirst and conditions, and supplement with electrolytes so you get both fluid and salts
- Caffeine: Plan when you want caffeine intake to fit in, and schedule your intake accordingly
Many stomach issues arise not only because of caffeine, but because:
- Fuel is taken very concentrated all at once
- Too little fluid is consumed relative to the amount of gel or chews
- New products are first tested on race day itself
If you want a simple way to combine carbs and hydration in one bottle, you can use Carbo Race Electrolyte as part of your overall fueling plan.
Safety tolerance and typical pitfalls
For most healthy adults, moderate amounts of caffeine are considered acceptable when kept within the general recommendations. Still, there are some things you should be aware of when planning your strategy.
Tolerance and daily coffee consumption
The body can get used to some of caffeine’s effects, for example feelings of restlessness. Research suggests, however, that caffeine can also have an effect in regular coffee drinkers. You therefore don’t necessarily need to remove all coffee leading up to a competition to be able to assess your response, but you can choose to cut back a bit and test what works for you.
Possible side effects at high amounts
With high caffeine intake, some people experience, among other things:
- Nervousness and restlessness
- Palpitations
- Sleep problems
- Gastrointestinal issues such as heartburn, nausea, or diarrhea
- Headache
Caffeine can also produce a dependence-like reaction with mild withdrawal symptoms such as headache and fatigue if you stop abruptly after a period of high consumption.
Who should be extra cautious
Some groups should be particularly mindful of their caffeine intake:
- People with cardiac arrhythmias or untreated high blood pressure
- People with pronounced anxiety, restlessness, or sleep problems
- Pregnant women, where the recommendation is typically to stay at about 300 mg of caffeine per day
- Children and adolescents, for whom high amounts of caffeine are generally discouraged
If you are unsure whether caffeine is relevant for you, it’s a good idea to talk to a doctor, dietitian, or other health professional before making significant changes to your caffeine consumption.
Pitfalls you can easily avoid
Some of the most common practical mistakes can be avoided with a few adjustments:
- Testing a high caffeine dose for the first time on race day itself
- Taking a large amount of caffeine on an empty stomach right before the start
- Consuming caffeine so late that it affects night-time sleep after evening training or evening competitions
- Believing that more is always better, even though higher doses often primarily increase the risk of side effects
Short answers to frequently asked questions
Below you’ll find short answers to some of the questions that often come up when endurance athletes begin working strategically with caffeine.
- Whether caffeine can contribute to endurance performance for some
- How much caffeine is typically used in endurance studies
- Whether coffee can work just as well as capsules or gel
- Whether daily coffee consumption can affect the perceived effect in competition
- How caffeine can affect fluid balance in people who are used to consuming it
- Whether caffeine is legal under current anti-doping rules
If you want to use caffeine more purposefully in your training, a good place to start can be a moderate dose that you test on long training sessions, where you also have your energy and fluid under control. Then you can adjust up or down, depending on how both your body and your stomach respond.
For some, caffeine can be a useful supplement when you want support for focus and perceived exertion in the hardest kilometers, but training, recovery, and an appropriate energy and fluid plan remain central factors for your performance.