RPE
Rate of Perceived Exertion
Short definition
Subjective rating of exercise intensity on a scale (often 6–20 or 1–10).
Full definition
RPE rates perceived effort (Borg 6–20 or modified 1–10). In resistance training an RIR-based RPE is common: 10 = no reps left, 9 = 1 rep in reserve, etc., helping auto-regulate load.
Examples
An RPE 8 set means 2 reps in reserve.