Before you consider how much caffeine you should aim to consume DURING training and races, it’s worth taking a step back and answering two key questions:
- Should I actually be using caffeine as part of my fueling strategy?
- How should I use caffeine BEFORE exercise?
If you’re in the majority of the population who are likely to benefit from using 1,3,7 trimethylxanthine (to use caffeine’s snappy chemical name), this article provides a starting point for you to do some trial and error during training to see what works best for you.
As with most performance-enhancing aspects of sports science, there’s no ‘one size fits all’ blueprint for how everyone should use caffeine for best results.
Your own use of caffeine will be very individual to you, so it’s best to view what follows as intelligent guidelines to get you started on your own journey and nothing more prescriptive than that…
How to use caffeine during exercise
When starting to work out your caffeine needs during exercise, you’ve got two major variables to play with:
- Amount of caffeine
- Timing of caffeine
The guidance for both timing and amount of caffeine will vary depending on the total duration of your workout or event. To account for this, we’ve broken our advice down across several time brackets:
Exercise duration: 0-3 hours
If you’ve followed the guidelines on how to pre-caffeinate before exercise (i.e. 3-6mg of caffeine per kg (1.4-2.7mg per lb) of bodyweight in the 60 minutes prior to starting), then theoretically this dose should still be in your system by the end of an event lasting 0-3 hours, because caffeine typically has a half-life of ~4-5 hours.
In practice, we know that many athletes competing for 2-3 hours (e.g. during a marathon or Olympic distance triathlon) believe that it’s beneficial to consume caffeine in the later stages too.
How much of this is a purely psychological belief versus a genuine ergogenic effect is unclear. So, some experimentation with this approach is recommended.
How to use caffeine during exercise lasting 0-3 hours:
For most athletes, pre-caffeinating during the hour before exercise will be enough.
But you may wish to consider consuming a dose in the region of 100-200mg during exercise as well (e.g. 1 or 2 strategically timed PF 30 Caffeine Gels).
It’s worth remembering that it will take at least 15 minutes for caffeine to be absorbed into your bloodstream and levels in your blood won’t peak until ~45-60 minutes after you take it in.
As such, consuming it too late will result in the effects kicking in after you’ve crossed the finish line, which isn’t ideal unless you’re hoping to have enough energy to go ‘big’ on the dance floor during your post-race celebrations!
So, try to consume your caffeine dose ~45-60 minutes before you want to see the biggest effect in order to maximise the impact on your performance.
Malcolm Hicks ran a 2:23 marathon at the Tokyo Olympics and took a total of 200mg of caffeine on board in tablet form towards the latter stages of the race.
Exercise duration: 3-5 hours
For slightly longer races, it’s also worth pre-caffeinating with 3-6mg of caffeine per kg of bodyweight (1.4-2.7mg per lb) during the 60 minutes before you start exercising.
You can then benefit from ‘topping up’ with small, regular doses (~50mg) or slightly larger, less frequent doses (~100mg) throughout. This can help stave off mental and physical fatigue as your pre-race dose wears off.
Depending on your rate of metabolism, caffeine’s half-life in your body is ~4-5 hours. So, as the caffeine present from pre-caffeinating before the race decays away, you can periodically replenish the levels in your blood to try to retain the benefits.
How to use caffeine during exercise lasting 3-5 hours:
The recommended caffeine dosage for performance during events lasting 3-5 hours is ~3-6 milligrams per kilogram (1.4-2.7mg per lb) of bodyweight, which includes the pre-caffeination dose you take in the 60 minutes before exercise.
So, the appropriate range for a 70kg (150lb) athlete would be in the region of ~200-400mg.
The source of the caffeine (i.e. capsule, gel or chew) you consume during exercise doesn’t seem to be overly important, although caffeinated gum is absorbed faster (within 20 minutes) and may be the preference if a ‘quick hit’ is ever required.
We’ve conducted case studies with very competitive middle distance triathletes and the average caffeine intake we’ve seen is 3.5mg/kg BW (n=15, range; 0.67-6.25mg/kg). The average duration of racing for these guys and girls was ~4 hours and 8 minutes.
Research has investigated doses greater than 6 mg/kg and shown that up to ~9-12mg/kg BW can be tolerated by some, but it doesn’t appear to deliver any further benefit to an athlete’s performance versus a more moderate dose.
If you’re someone who’s sensitive to caffeine, a lower dose (e.g. 1-3 mg/kg) may be all that’s required to stimulate caffeine’s ergogenic effect; hence the repeated recommendations to use trial and error in training to find out what works for you.
A 70kg (154lb) triathlete competing in an IRONMAN 70.3 race
- Pre Race - A medium coffee in the morning (~50-100mg of caffeine) with breakfast (+ PH 1500 preload). Consume 1-2 PF 30 Caffeine Gels (~100mg) during the 30 minutes before you start
- During the race - Take 1 x PF 30 Caffeine Gel on the bike (100mg), another on the run (100mg) and supplement this with some coke collected at aid stations for smaller top-up doses (Coke contains ~10mg per 100ml or ~3.5oz).
- Following this regime would average out in the region of ~5-6mg of caffeine per kilogram of bodyweight (i.e. towards the upper end of the recommended dosage of 3-6mg per kilogram)
Exercise duration: 5-12 hours
It’s during these longer durations that the general 3-6mg per kg of bodyweight guideline for caffeine dosages may start to become less useful.
This is because the guidelines don’t account for these very long durations when you may completely metabolise the caffeine you consumed pre-race and during the early stages. So, a larger total amount is needed to keep your caffeine levels ‘in the zone’ as the race wears on.
How to use caffeine during events lasting 5-12 hours:
During the bike leg of a triathlon, you might use 2-3 PF 30 Caffeine Gels (100mg caffeine each) and then regular sips of coke on the run leg.
An example: In our long distance triathlon case studies, the average caffeine dose is high at 6.48 mg/kg (n=9, range; 0.68-11.31 mg/kg) in the more competitive athletes we’ve studied (the average race duration for these athletes is ~9 hours and 45 minutes, which is clearly very fast and it’s worth bearing in mind that this is a relatively ‘elite’ group).
Fenella Langridge’s race strategy at IM Mallorca involved consuming small, regular caffeine doses throughout to reach 5.26mg/kg.
Exercise duration: 12+ hours
For more extreme race durations, there’s often a benefit to strategically using caffeine in the latter stages (during the night time specifically), when fatigue and tiredness due to circadian rhythms can limit your performance.
As such, pre-caffeinating beforehand might not be necessary if you’re taking part in these very long events.
There’s even an argument to keep pre-race caffeine to a minimum (i.e. enjoying your usual morning coffee in order to prevent withdrawal symptoms, without pre-caffeinating during the 30-60 minutes before you set off), so that you can then enjoy the full benefits of topping up on caffeine later.
One study found that adopting a strategic use of caffeine, particularly when sleep deprived or mentally fatigued, improved time to exhaustion by ~14%. Whilst that’s only one study, it hints at the fact that using caffeine intelligently can have a positive effect in negating tiredness.
Certainly a key time when caffeine can be especially useful is when you need to fight your natural sleep-wake cycle (i.e. overnight when DNF rates in ultras tend to peak).
How to use caffeine during exercise lasting >12 hours: Rather than just drip feeding yourself caffeine throughout an ultra, you may find it useful to ‘save it’ for when mental fatigue/tiredness is at its highest during the later stages and overnight.
Reaching for higher doses (~200mg) at this point then gives more of a ‘kick’ and may help you deal with the sleep-deprivation ‘demons’ more effectively.
An example: Due to the length of these races, the overall dosage across a 12-24 hour period can easily exceed the 3-6mg per kilogram of bodyweight guideline.
For example, Damian Hall consumed a total of 1,390mg over the 52 hours and 35 minutes he was racing during The Spine Race. This averaged an intake of approximately 22mg per kilogram of bodyweight(!).
Observation and practical experience would tell us that this is often OK (and can be warranted) under these circumstances, despite being well in excess of the 3-6mg per kilogram of bodyweight guidance that applies to shorter durations.
Recommendations for athletes
Ultimately, only once you understand whether you should incorporate caffeine into your fueling strategy and have worked out your pre-exercise caffeine needs, you should start to experiment with your caffeine intake during big training sessions and races.
These recommendations should be used as a guide for you to begin experimenting with your own caffeine intake during exercise, rather than a prescriptive set of rules.
Remember, how you use caffeine during exercise will be highly individual and influenced by your personal preference, race duration, previous experiences, tolerance, sensitivity and how often you use caffeine.
If you’re unsure about your own caffeine needs, book a free one-to-one video consultation with a member of the Precision Fuel & Hydration team and we’ll be happy to discuss how best for you to use caffeine as part of your fueling strategy.