When should you take caffeine during a triathlon?

Caffeine is one of the few supplements that most experts agree can boost endurance performance. But, as with most ergogenic aids, you have to use it intelligently to get the best results.

Caffeine is one of the few supplements that most experts agree can boost endurance performance. Credit: mikroman6/getty

Three things to remember are that dosage, timing and your individual tolerance to caffeine are all key to using it during a triathlon. Research suggests 2-6mg per kg of bodyweight is the optimal range for most endurance athletes. Less is unlikely to have an effect; any more could prompt adverse side effects.


The ‘sweet spot’ is quite individual, but starting with around 2-3mg/kg is a good ballpark figure. Ideally you should use the lowest dose that delivers a decent response. For this reason, using products like tablets, drinks or energy gels with exact quantities of caffeine is preferable to just guessing your dosage.

Caffeine takes around 45-60mins to peak in the bloodstream after consumption. It’s absorbed via the stomach and intestines with effects lasting about 3hrs. This means that for shorter sprint and Olympic races, taking a dose 1hr before swim start is ideal and you shouldn’t need more during your race. For middle, long or ultra races, a similar 60min pre-start dose can be followed up with a drip feed approach during the race. This can provide a welcome boost when you’re starting to flag and the initial hit wears off.


From a genetic point of view, people’s bodies process caffeine with different levels of effectiveness. Some handle it well, while others get the ‘jitters’. Your day-to-day caffeine habits affect tolerance, too, so you need to know how your body handles it before using on race day. If you’re a regular coffee drinker, abstaining or cutting back 5-6 days before your race can increase potency quite dramatically. Just be aware that going fully ‘cold turkey’ can bring on headaches and other withdrawal symptoms if you’re a regular user, so it’s probably best to step down consumption over a few days rather than just stopping overnight.

Are energy gels with caffeine worth it?

Can caffeine boost your performance in a triathlon?

Caffeine: what, when and how much to take

Does coffee dehydrate you?

Energy gels: what you need to know