One-repetition maximum (1RM)

The one-repetition maximum (1RM) is the heaviest load you can lift through a full range of motion, for one all-out rep with proper form. It is the gold-standard measure of your maximal dynamic strength. Percentage-based training zones are usually set from your 1RM (for example, 60 to 70% for muscle growth, 85% or more for strength). Direct testing carries injury risk in untrained or older people. So validated prediction equations (like Epley and Brzycki) can estimate your 1RM from sub-maximal reps-to-failure tests. But the accuracy drops above 5 to 10 reps. Progressive overload is put into practice as periodic increases in your 1RM over a training cycle. And a declining 1RM with age reflects both sarcopenia (muscle loss) and dynapenia (strength loss).

Last reviewed: June 22, 2026

This definition is educational and is not medical advice, a diagnosis, or treatment. Talk to a doctor about any health decisions. Read our full medical disclaimer