Caffeine and Endurance Performance: How Much, When and Does It Work in Chews?

Caffeine is one of the few supplements in endurance sport with a genuinely strong evidence base behind it. Where most "performance" products live in the realm of marginal, hard-to-measure gains, caffeine and endurance performance have been studied together for decades, with meta-analyses consistently showing improvements of 2-4% in time-trial performance. That's not a rounding error — for a three-hour marathon runner, 2-4% is somewhere between four and seven minutes.

But the research is also full of nuance that gets lost in supplement marketing: dose matters enormously, timing matters, and the format you take it in — coffee, tablet, gel or chew — changes how predictably it hits your system. This guide sets out the actual numbers, so you can build a caffeine strategy instead of guessing.

How Caffeine Improves Endurance Performance

Caffeine works primarily by blocking adenosine receptors in the brain. Adenosine builds up during exercise and is part of what makes effort feel harder as a session goes on — it dampens central nervous system activity and contributes to perceived fatigue. By occupying those receptors, caffeine blunts that signal, which is why the dominant effect isn't more raw muscle power but a lower rating of perceived exertion (RPE) at a given pace or wattage. Riders and runners consistently report that a hard effort simply feels more manageable, which lets them sustain intensity for longer.

There's a secondary effect too: caffeine mobilises free fatty acids from adipose tissue, sparing muscle glycogen slightly in the early stages of exercise. This effect is smaller than once believed and is now considered a minor contributor compared with the central nervous system pathway, but it's still part of the picture on rides and runs over 90 minutes.

The Right Dose: 3-6mg per Kilogram of Bodyweight

This is where most athletes get it wrong — either taking too little to notice anything, or stacking so much caffeine that they end up jittery, nauseous or unable to sleep the night before a race. The research window that consistently produces performance benefit is 3-6mg per kilogram of bodyweight, taken as a single dose. For a 70kg athlete, that's 210-420mg — roughly two to four cups of filter coffee, or the equivalent in caffeinated chews or gels.

Doses above 6mg/kg don't tend to add further benefit and increase the risk of side effects: elevated heart rate, GI upset, and anxiety, none of which you want mid-race. If you're caffeine-naive or sensitive, start at the lower end — even 2-3mg/kg has been shown to produce a measurable effect, and it's a much safer place to test from than jumping straight to 400mg on race morning.

Caffeine and Endurance Performance: Getting the Timing Right

Peak plasma caffeine concentration is typically reached 45-60 minutes after ingestion, with a meaningful effect lasting three to five hours. For a single dose before a race or key session, 45-60 minutes pre-start is the standard recommendation — early enough that you're not still absorbing it on the start line, late enough that you're not fading before the finish.

For anything over two hours, a split-dose strategy tends to work better than one large hit at the start: something like 2-3mg/kg pre-race, then smaller top-up doses (50-100mg) every 60-90 minutes through the back half of the event, when perceived effort typically climbs fastest. This is exactly where caffeinated chews earn their place over coffee or tablets — they're easy to carry, dosed consistently, and don't require boiling water at kilometre 30.

Caffeine Tolerance: Why a Short Taper Beats Daily Loading

Habitual daily caffeine intake blunts the performance effect. Studies comparing habitual high consumers against caffeine-naive subjects consistently find a smaller ergogenic response in the former group — your adenosine receptors adapt to chronic caffeine exposure the same way they adapt to most stimulants. If you drink two or three coffees a day year-round, the 300mg you take before a race isn't hitting a "fresh" system.

The practical fix most sports scientists recommend is a short taper rather than a full withdrawal: cutting back to little or no caffeine for 3-7 days before a key event resensitises the receptors without the withdrawal headaches that come from stopping cold weeks out. Full abstinence for longer periods hasn't been shown to add much further benefit and carries a real cost in irritability and disrupted training, so a week is usually the sensible ceiling.

Practical guidance for putting this together on race day:

• Work out your dose from bodyweight (3-6mg/kg), not from a flat number you've seen on a label
• Trial it in a long training session first — never take a new dose or format for the first time on race morning
• Time your first dose 45-60 minutes before the start
• For events over two hours, plan small top-up doses every 60-90 minutes rather than one large hit
• Taper your everyday intake for 3-7 days beforehand if you're a regular coffee drinker

Does Caffeine Work as Well in a Chew as in Coffee?

Yes, and arguably it works more reliably. Coffee's caffeine content varies wildly by bean, roast and brew method — a "large coffee" could be delivering anywhere from 95mg to over 300mg, which makes it a poor tool for precise dosing on race day. A chew with a stated caffeine content per serving removes that guesswork entirely, which matters when you're trying to stay inside that 3-6mg/kg window rather than accidentally doubling it.

Absorption speed is broadly similar between chews and coffee, since both are swallowed and absorbed through the gut rather than the mouth (this is different from caffeinated gum, which is absorbed faster through the oral mucosa). The practical advantage of a chew is portability and control: you can carry precisely the dose you need for the back half of a long ride without having to plan a coffee stop into your nutrition strategy.

What We Use at FTP Endurance Fuel

We've deliberately kept our own Tart Cherry Energy Pastilles and Mixed Fruit Energy Pastilles caffeine-free. That's not an oversight — it's so you can layer caffeine on top of your fuelling in whatever dose and timing suits you, rather than being locked into whatever amount happens to be baked into a single gel or chew. Our pastilles are built to do one job well: deliver a clean glucose-fructose carbohydrate hit (in mixed fruit or tart cherry flavour) without adding stimulants you might not want on every single serving.

In practice, that means athletes we work with often pair our chews with a separate, precisely-dosed caffeine source — a caffeinated gel, tablet or even a flask of coffee before the start — so the caffeine dose is controlled independently of the carbohydrate dose. If you're still working out your carbohydrate strategy before layering caffeine on top, our Taster Pack is a low-risk way to trial both flavours, and the full range of bundles covers everything from a single long session to a full race block.

Caffeine is one of the cheapest, best-evidenced performance tools available to endurance athletes, but only when the dose and timing are deliberate rather than habitual. Work out your bodyweight-based dose, test it in training rather than on race day, and keep it separate from your carbohydrate strategy so you can adjust each independently. If your carb fuelling still needs sorting first, start with our bundles and build your caffeine plan on top of a strategy that's already dialled in.