Strong evidence · Performance
Caffeine
Strength, endurance, alertness and perceived effort
Strong evidence
Multiple good studies and reviews point the same way.
One of the best-researched performance aids: the ISSN position stand (2021) concludes that caffeine improves performance in many, but not all, studies, in trained and untrained people alike. Studies saw effects on muscular endurance, speed, strength and sprinting.
- Dosage
- 3–6 mg per kilo of body weight
- Timing
- About 60 minutes before your workout
- Approx. price
- €2–5 per month
Watch out
Doses around 9 mg per kilo give many side effects with no extra benefit, and the minimum effective dose may be as low as 2 mg per kilo. Caffeine can disturb your sleep or cause restlessness; how much varies from person to person, partly for genetic reasons. So don't take it late in the day.
Frequently asked questions about supplements
How much Caffeine per day?
3–6 mg per kilo of body weight
When should you take Caffeine?
About 60 minutes before your workout
Does Caffeine really work?
Strong evidence. Multiple good studies and reviews point the same way.
What does Caffeine cost?
€2–5 per month
Basics first, then the tub
Supplements are called supplements because they add to something. Sleep, a protein intake that hits your protein calculator , a programme where you lift progressively heavier and enough food together do a hundred times more than the best-researched item on this list. Once those are in place, creatine, caffeine and vitamin D in winter are the three you can spend money on with a clear conscience — for less than ten euros a month combined.
Sources
- Guest NS et al. (2021). International society of sports nutrition position stand: caffeine and exercise performance. J Int Soc Sports Nutr 18:1. (position stand)
More supplements in this category
Last updated: October 2026
This page summarises scientific research and is not medical advice. If you take medication, are pregnant or have a liver, kidney or thyroid condition, discuss supplements with your doctor or pharmacist — even the innocent-looking ones.
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