RIRReps in Reserve
How many more reps you could have done — a way to gauge proximity to failure.
RIR (Reps in Reserve) is the number of additional reps you could have completed at the end of a set before hitting failure. Stopping a set at 2 RIR means you could have done two more.
It matters because training close to — but not always at — failure is effective for growth while managing fatigue. RIR gives a practical target for how hard to push each set.
It is the mirror image of RPE: 0 RIR corresponds to RPE 10 (true failure), 2 RIR to RPE 8, and so on.
Put it to use
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Written and reviewed by Mathew Beale — MSc Biotechnology, University of Reading.
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