CAFFEINE FOR LONG DISTANCE RUNNERS & ULTRARUNNERS - Do it right!

Hey! I’m Irene — PhD in Biomedicine, with an MSc in Sports and Exercise Science and Medicine, and a certified running & ultrarunning coach. I have extensive experience working with runners of all sorts, from helping them rehab and get back to running, to supporting them through crazy ultramarathons and stage ultras.

My coaching is grounded in evidence-based science, not social media trends. If you need help with your training and/or race nutrition, you can book a call with me here: 👉 https://calendly.com/train4bodymind/

About caffeine for runners

Caffeine is one of the most effective and well-researched ergogenic aids available.

For endurance athletes, caffeine can:

• Reduce perceived effort

• Improve alertness and concentration

• Help maintain pace when fatigue sets in

• Improve endurance performance

• Counteract sleep deprivation during long races

The goal is not to feel wired.

The goal is to maintain performance for longer.

For that, the right timing and dose are needed. And no, not all runners respond the same way to caffeine. So forget the post from your favourite influencer. You need to do what works for YOU 🫵

1. Not everyone responds the same

One of the biggest mistakes runners make is copying someone else’s caffeine strategy.

Caffeine metabolism is influenced by genetics, particularly the CYP1A2 gene. However, genetics is only part of the story. Habitual caffeine intake, medications, hormones, smoking status and individual sensitivity can also influence how you respond.

Some runners are:

Fast metabolisers

• Feel the effects quickly

• Effects may wear off sooner

• Often tolerate larger doses better

  
  

Slow metabolisers

• Effects last much longer

• More prone to jitters, anxiety and sleep disruption

• Often benefit from lower doses

  
  

I’m personally much more this type of runner.

This is why two runners can take the same caffeine gel and have completely different experiences.

For female athletes

Women taking oral contraceptives may metabolise caffeine more slowly, meaning the effects can last significantly longer.

This is another reason why personalised testing is essential.

Take home message: Your strategy must be personalised.

2. How much caffeine should you take?

Research consistently shows benefits with:

3-6 mg/kg body weight

Personally, for endurance and ultra-endurance events, I rarely see a reason to recommend someone start near 6 mg/kg. More is not better.

Doses above this range are more likely to increase side effects without giving extra performance benefits.

Too much caffeine may cause:

• Jitters

• Anxiety

• Increased heart rate

• Dizziness

• GI upset

• Difficulty eating

• Poor sleep after the race

  
  

Many runners obtain meaningful benefits with: 2-3 mg/kg

Start low and only increase if needed.

Also, check your gels, chews, gums, tablets... A lot of products already contain high doses of caffeine. For example, a Maurten caffeinated gel contains around 100 mg. For me, that is more than enough to get going for several hours. In shorter races around 50K or under, I may only need one caffeine gel.

But you may work differently.

This is why it is so important to test in training.

Some runners find they become less sensitive to caffeine when consuming large amounts daily, which is another reason why testing your strategy in training is important.

3. Timing your caffeine

Most caffeine is absorbed within approximately 45 minutes.

Peak blood concentrations typically occur between: 30-120 minutes. Sometimes longer.

The exact timing varies between individuals.

Because of this:

• Test caffeine in training

• Record when you take it

• Note when you feel the strongest effects

• Write it down

• Build your race strategy around your own response

  
  

Do not guess this on race day.

4. Marathon strategy

For races lasting 2-5 hours, there are a few options.

Option 1: full dose before the start

Take your planned dose around 45-60 minutes before the start.

This may work well if you tolerate caffeine well and know it does not upset your stomach.

Option 2: split your dose

Example:

• 150 mg pre-race

• 50-100 mg during the second half

Many runners find split dosing provides more stable energy levels.

Option 3: small late-race boost

If the effects of caffeine are strong for you, you may prefer a smaller dose of 50-100 mg around 2-3 hours before the end of the event.

This can give you a useful push later in the race, when fatigue is higher.

Again, this needs to be tested in training.

5. Ultra-running strategy

Ultra-running is different and this section is mainly referring to longer ultras, especially events over 100K.

The biggest limiter is often not just muscular fatigue.

It is also:

• Alertness

• Concentration

• Sleep pressure

• Decision making

• Motivation when everything feels hard

  
  

For races extending into the night, consider saving a substantial portion of your caffeine for:

• The first night section if you started in the morning

• The first morning if you started running through the night

• The pre-dawn low point

• Periods of increasing sleepiness

• Sections where concentration really matters

  
  

If your race starts overnight, avoid using all your caffeine early.

If you are used to having coffee in the morning, using caffeine once the morning arrives may also help you work with your normal circadian rhythm.

In long ultras, you do not want to become too dependent on caffeine too early. Once you start relying on caffeine to maintain alertness, you will often need additional doses later in the race to maintain a similar effect.

A more conservative approach often works better.

Remember: more is not always better.

6. Top-ups: don’t wait until you’re exhausted

Many runners wait until they feel terrible before taking more caffeine. That is often too late.

A better strategy is to top up before performance starts dropping.

Remember, caffeine usually peaks around 30 minutes to 2 hours after intake. The effects then start declining a few hours later, but this depends on the individual. In training, track when this happens for you. Then you will know when to take the next dose.

A practical guideline for long races is: 25-100 mg every 2-4 hours. If you are a slow metaboliser, like me, you may be able to wait longer between doses.

The exact amount depends on:

• Body size

• Previous caffeine intake

• Sensitivity

• Race duration

• Time of day

• Sleep pressure

• GI tolerance

  
  

Smaller, more frequent doses are usually easier to manage than large caffeine hits.

For instance, you may take half of a caffeinated gel and then take the other half a couple of hours later.

7. Keep track of total caffeine intake

One of the biggest mistakes I see in ultras is runners accidentally consuming far more caffeine than they planned.

Remember that caffeine can come from:

• Gels

• Chews

• Cola

• Energy drinks

• Coffee

• Pre-workout products

• Aid station products

  
  

Many runners do not realise how quickly these doses add up.

You may think you only had “a few gels and some cola,” but by the end of a long race, that could become a very large caffeine dose.

Always know how much caffeine you have consumed and have a rough plan before race day.

Your goal is not to take as much caffeine as possible. Your goal is to take the minimum amount that gives you the maximum performance benefit.

8. Caffeine and carbohydrate intake

Caffeine does not directly “burn through glycogen.”

However, if caffeine allows you to run harder, you will likely use more carbohydrate because your intensity is higher.

This means:

If caffeine increases your output, your fuelling strategy must keep up. Otherwise, you may rely on your glycogen reserves earlier. This is particularly important in shorter races where caffeine may help you push harder. Do not increase caffeine while neglecting carbohydrate intake. Caffeine is not a replacement for carbs.

9. Caffeine and hydration

A common myth is that caffeine causes severe dehydration.

Current evidence does not support this in trained athletes consuming normal race-day doses.

However:

• Large doses may increase bathroom stops in some individuals

• Fluid requirements still need to be met

• Hot conditions may increase hydration needs

• Race-day hydration strategies should be practised in training

  
  

Do not blame caffeine for everything. But do not ignore how your body responds either.

10. Does caffeine cause cramps?

There is currently little evidence that caffeine directly causes muscle cramps.

When cramps occur during races, they are more likely related to:

• Fatigue

• Pacing

• Muscular damage

• Inadequate fuelling

• Individual susceptibility

  
  

If caffeine seems to trigger cramps for you personally, take that seriously. But do not automatically blame caffeine.

Look at the whole picture:

• Did you pace too hard?

• Did you fuel enough?

• Were you underprepared for the terrain?

• Did you take more caffeine than usual?

• Was your hydration strategy tested?

  
  

Cramps are usually multifactorial.

11. Signs you’re overdoing it

Too much caffeine may cause:

• Anxiety

• Jitters

• Increased heart rate

• GI upset

• Dizziness

• Poor decision making

• Difficulty eating

• Difficulty sleeping after the race

• Feeling wired but not actually running better

  
  

If these occur, reduce the dose. More caffeine rarely solves a caffeine problem.

Testing protocol before race day

Do not build your caffeine strategy during the race.

Build it in training.

Session 1: baseline

No caffeine.

Establish a baseline.

Track how you feel, your pace, your heart rate and your perceived effort.

Session 2: low dose

Try around 2 mg/kg.

Assess your response.

Did it help?

Did it cause anxiety, GI issues or sleep disruption?

Session 3: same dose, different timing

Use the same dose but change the timing.

For example, test it 45 minutes before a session, then test it 90 minutes before another similar session.

This helps you understand when caffeine peaks for you.

Session 4: race-day top-ups

Test smaller top-ups during a longer run.

Write down the timing.

Assess your response.

Track:

• Energy levels

• Alertness

• Pace

• Heart rate

• GI comfort

• Sleep quality that night

• Total caffeine intake

• Timing of every dose

• Whether the dose came from gel, coffee, cola or another source

  
  

Be careful not to overdo caffeine in training. Remember, a good night’s sleep is often more important for adaptation than squeezing a tiny bit more out of one session.

Key takeaways

✓ Start with the lowest effective dose

✓ Test timing in training

✓ Don’t copy someone else’s strategy

✓ Use caffeine strategically during long ultras

✓ Track total caffeine intake

✓ Stay on top of carbohydrate intake

✓ More is not always better

✓ Never try a new caffeine strategy on race day unless it is a practice race

The best caffeine strategy is not the one that contains the most caffeine.

It is the one that gives you the biggest performance benefit with the fewest side effects.

Questions? Get in touch. I'm always happy to help and I love working with motivated runners and ultrarunners.