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RPE and RIR: dial in your intensity

How to use perceived exertion to train just hard enough — not too easy, not to failure.

RPE and RIR

RIR (Reps In Reserve) is how many reps you have left before technical failure. RPE (Rate of Perceived Exertion) on a 1–10 scale is the mirror image: RPE 8 ≈ 2 RIR.

Why it's useful

Always training to failure increases fatigue without producing more growth. Stopping 1–3 reps short of failure (RPE 7–9) delivers almost all of the stimulus at a lower cost.

In practice

  • Compound lifts: keep RPE 7–8 on most working sets.
  • Isolation exercises: can be taken closer to failure (RPE 9–10).
  • Log RPE to guide progression week to week.