Caffeine is the one supplement with decades of evidence behind it, and a mug of coffee gives you most of what a pre-workout tub does at a fraction of the price. Here is how to use it and when not to.
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Does it work?
Yes, modestly. Caffeine makes hard effort feel a little easier, so people do a bit more work in the session. For a 6am class the bigger effect is simply being awake. It does not burn fat on its own and it does not replace sleep, which is the thing most people who reach for it are short of.
How much and when
For most adults a strong coffee, roughly 100 to 200mg of caffeine, 30 to 60 minutes before training is plenty. Sports science studies use higher doses, but the side effects climb faster than the benefit. The UK guideline for healthy adults is to keep the whole day under about 400mg, which is three or four coffees, and pregnant women are advised to stay under 200mg. Caffeine hangs around for hours, so anything after early afternoon will cost you sleep, and lost sleep costs you far more than the coffee gained.
What is in a pre-workout tub
- Caffeine, usually 150 to 300mg a scoop, sometimes more. This is the bit that does something.
- Beta-alanine, which causes the tingling. Harmless, mildly useful for very hard efforts, mostly there so you feel it working.
- Citrulline or arginine for the "pump", with a small effect at best.
- Sweeteners, colours and a proprietary blend that hides the doses.
If you like the ritual, buy one with the doses printed on the tub and take half a scoop. If you do not, coffee is cheaper and you know what is in it. The supplements guide covers the few things worth your money.
Leave it alone if
You are pregnant or breastfeeding, under 18, have a heart condition, high blood pressure or anxiety, or you are on medication that says to avoid it. If you are unsure, ask your GP or pharmacist, not a supplement shop. And if your heart is racing or you feel shaky in a session, tell me and we ease off.
My answer when people ask
Sleep seven hours, eat something two hours before, have a coffee if you want one. That is the pre-workout.