Knowledge base
Source-based training science — free. The same content powers our AI coach.
To the exercise libraryFundamentals
Progressive overload: the foundation of all progress
Why the body only changes when you gradually increase the load — and how to do it in practice.
beginnerRPE and RIR: dial in your intensity
How to use perceived exertion to train just hard enough — not too easy, not to failure.
intermediateHow long should you rest between sets?
How rest duration affects strength and growth — and what the research says.
beginnerA warm-up that works
How to warm up effectively without wasting energy.
beginnerCommon beginner mistakes
The most common errors that stall progress — and how to avoid them.
beginner