RPE and Reps in Reserve (RIR) Explained
Updated
Short answer
RPE (rating of perceived exertion) and RIR (reps in reserve) describe how hard a set was. RIR is the number of extra reps you could have done with good form: 2 RIR means you stopped with two left. On the lifting RPE scale, RPE 8 equals 2 RIR and RPE 10 means no reps left. Most working sets for strength and muscle land around 1 to 3 RIR.
The scale
| RPE | Reps in reserve | Feels like |
|---|---|---|
| 10 | 0 | Could not do another rep |
| 9 | 1 | One more rep possible |
| 8 | 2 | Two more possible |
| 7 | 3 | Bar speed still quick |
| 5–6 | 4–6 | Warm-up or technique weight |
This repetitions-in-reserve version of RPE for lifting was described by Zourdos and colleagues, who found experienced lifters rated proximity to failure more accurately than novices.
Using it
- Beginners: aim for 2 to 3 RIR. You will underestimate at first; that is normal.
- Check yourself now and then by doing a last set to near failure on a safe exercise (a machine or dumbbells, not a heavy barbell squat without safeties).
- If a planned set at RPE 8 feels like RPE 9.5, take some weight off: that is a sign of fatigue.
Session RPE for whole workouts
A different tool, session RPE, rates a whole session from 0 to 10 and multiplies by the minutes to estimate training load. It is useful for comparing gym work with sport or running.
Frequently asked questions
Do I need to train to failure?
No. Sets taken close to failure (around 1 to 3 reps in reserve) drive most of the benefit, with less fatigue and lower injury risk than grinding every set to failure.
Is RPE the same as heart rate?
No. RPE is how hard it feels. For lifting, heart rate is not a useful measure of effort.
Sources
- Zourdos et al. (2016). Novel resistance training-specific rating of perceived exertion scale measuring repetitions in reserve. J Strength Cond Res 30(1)
- Foster et al. (2001). A new approach to monitoring exercise training. J Strength Cond Res 15(1)
- American College of Sports Medicine (2009). Progression models in resistance training for healthy adults. Med Sci Sports Exerc 41(3)