One of the few ergogenic aids with solid evidence behind it, and it is legal. The dose has been studied and it is calculated per kilo of bodyweight — you are probably taking less than you need.
A legal aid with evidence behind it
Caffeine came off the World Anti-Doping Agency's prohibited list in 2004, and it is today one of the few ergogenic aids with broad, consistent scientific support.
This isn't supplement marketing: there are hundreds of controlled studies, and the effect repeats across endurance, strength and team sports.
The dose is calculated per kilo
This is what's missing from almost every article on the subject, and it's the only thing that makes the information actionable.
The best-supported range is 3 to 6 mg of caffeine per kilo of bodyweight. For a 70 kg person, that's between 210 and 420 mg.
| Weight | Dose (3 mg/kg) | Equivalent to |
|---|---|---|
| 60 kg | 180 mg | ~1 long double espresso |
| 70 kg | 210 mg | ~2 double espressos |
| 80 kg | 240 mg | ~2 double espressos |
| 90 kg | 270 mg | ~2 doubles or 1 large filter |
Translated: a single 70 mg espresso before training falls well short for most people. And going above 6 mg/kg doesn't improve performance — it only adds a racing heart, tremor and stomach trouble.
When to take it
Peak blood concentration arrives 45 to 60 minutes after ingestion. To train at 19:00, the coffee goes in around 18:00-18:15.
For long sessions — more than two hours of cycling or running — a small second dose midway maintains the effect without doubling the initial one.
What it actually helps with
Endurance. This is where the effect is clearest and most studied. The main mechanism isn't metabolic: it's that it reduces perceived exertion. The same pace feels easier, so you hold it longer.
Strength and power. Real but more modest gains, mostly in repeated sets and in the second half of a session, when fatigue bites.
Focus and reaction time. Relevant in team sports, racket sports and any technical discipline, especially late in a match.
Caffeine doesn't make you stronger. It makes the effort feel less hard, and that translates into holding more intensity for longer.
Coffee or a supplement
Studies tend to use anhydrous caffeine in capsules because it allows exact dosing, and from that comes the myth that coffee doesn't count. It isn't true: coffee works identically, with the caveat that the dose is less precise because it depends on the bean and the brew.
If you compete and want precision, capsules give it to you. For training, a well-calculated coffee does the same job and tastes infinitely better.
Training fasted
A black coffee before a fasted session doesn't break the fast in any meaningful sense — it contributes essentially no calories. And since caffeine mobilises fatty acids, it fits that kind of session well.
With milk, no longer: at that point you're taking in protein and fat.
The limit: don't wreck your recovery
This is the part most often ignored, and the one that can cost you most.
Muscle recovers during sleep. Caffeine has a half-life of around 5 hours and reduces deep sleep even if you manage to fall asleep. Training at night on a high dose can give you a better session and a worse recovery — a poor trade over the medium term.
For evening training, either lower the dose or switch to decaf and accept training unaided that day.
When not to use it
If you have arrhythmias or heart conditions, check first. If it makes you anxious, don't force it: a jittery state does more harm than caffeine does good in technical sports. And if your stomach is sensitive, coffee on an empty stomach at a high dose can sit very badly.
The detail on metabolism, tolerance and limits is in the article on caffeine, and the stimulant-free alternatives in the decaf guide. Coffee is in the shop.
