Caffeine & performance: how much, when and for whom
The most popular ergogenic aid. How much helps, and when it backfires.
For most athletes, 3–6 mg of caffeine per kilo of body weight, about 45–60 minutes before the effort, improves endurance, focus, and perceived fatigue. Larger doses rarely help and often bring a racing heart, anxiety, and poor sleep.
Why caffeine "works"
Caffeine blocks adenosine, the molecule that makes us feel tired. The result is greater alertness, better focus, and the sense that the same effort "costs" less. That's why it's one of the few ergogenic aids with strong, consistent evidence, both for endurance and for explosive efforts.
How much of a dose?
The effective dose is 3–6 mg per kilo of body weight. For a 70 kg athlete, that works out to roughly 210–420 mg, about two to three cups of coffee, depending on the source. Start at the low end and only go higher if you tolerate it well.
When to take it
The key rule is timing: caffeine peaks about 45–60 minutes after you take it. So take it shortly before your warm-up, not once you've already started. For evening sessions, be careful: caffeine stays in your system for hours and can disrupt your sleep.
"With caffeine, 'more' doesn't mean 'better'. It just means more jittery."
When it backfires
Past a certain point, the benefits stop and the problems start: a racing heart, tremors, stomach discomfort, and anxiety that lowers performance instead of raising it. Poor sleep from taking too much, or taking it too late, also sabotages recovery, which is half the work of training.
Who it isn't for
Not everyone responds the same way: some people metabolise caffeine slowly and feel even small doses intensely. If you have arrhythmias, high blood pressure, anxiety, or are pregnant or breastfeeding, talk to your doctor or dietitian before using it as a performance tool.
Every case is different. We can look at your needs together.