The Lifts · L7
Calibrating Effort
"Stop 1–3 reps short of failure" only works if you can feel where failure is — and as a beginner, you almost certainly think it's closer than it is.
Your whole program runs on RIR — "leave 1–3 reps in the tank." But that instruction is useless if your internal "I'm done" alarm is wrong. The evidence says a beginner's alarm goes off way too early. This lesson recalibrates it, so your hard sets are genuinely hard and your volume actually counts.
1RIR and RPE — one simple scale
RIR (Reps In Reserve) is how many more reps you could have done. RPE (Rate of Perceived Exertion) is just the flip side on a 1–10 scale.1 Your "RIR 1–3" is simply RPE 7–9:
| RPE | Reps in reserve | What it feels like |
|---|---|---|
| 10 | 0 | Failure — last rep was an all-out grind |
| 9 | 1 | Definitely one left, no more |
| 8 | 2 | Two left; bar is clearly slowing |
| 7 | 3 | Three left; bar still moving well |
| 5–6 | 4–6 | Effort building, but reps still smooth |
2The beginner trap: you stop too early
Here's the finding that matters most. When untrained people are asked to predict how many reps they have left, they massively underestimate — they feel "almost done" while several clean reps remain. In one study of 141 people, less-experienced lifters underpredicted failure by ~4–5 reps; even experienced lifters were off by ~1–2.23
When you think "that's RPE 10, I'm done," you may actually be at RPE 5–6 with 4–5 reps left. If you stop there, your "hard" sets aren't hard, and your training is quietly under-dosed. The fix isn't to grind everything to failure — it's to learn what the top of the scale really feels like.
3Read the bar, not the feeling
The most reliable signal of approaching failure is involuntary bar slowdown: as you near failure the lifting phase gets slower even though you're pushing as hard as you can. Fast bar = reps in the bank.4 Play a set — lift reps, watch the speed, and rack when you'd stop. Then see how many you really had left.
4The cues that tell you you're close
- Bar slows on the way up. The last 1–2 reps "grind" — the objective gold-standard cue.
- Form starts to drift. Range shortens, the path wobbles, hips shoot up on a squat.
- The "$100 test." At the point you want to stop, ask: "If someone paid me $100, could I get 2 more clean reps?" If "easily" — you're at RIR 3+. If "maybe one, ugly" — you're at RIR ~1.
5How close to push — by goal
| For… | RIR | RPE | Why |
|---|---|---|---|
| Most hypertrophy sets | 1–2 | 8–9 | Close enough to recruit the big fibres, without trashing recovery |
| Heavy strength compounds | 2–4 | 6–8 | Technical lifts + heavy load — keep quality reps, stay safe |
| True failure (0 RIR) | rare | 10 | Occasional machine/isolation work or a calibration test only |
True failure is rarely needed: once you're within a rep or two, you've got the stimulus.1 Grinding to failure on heavy compounds just adds fatigue and risk.
6Your calibration routine
Pick one safe machine (leg press, machine chest press). (1) Once, take a set to true failure so you learn what 0 RIR feels like. (2) Each session after, predict the rep where you'll hit RIR 2 — stop there — then do one more set and count how many you actually had left. (3) Most beginners find they were stopping 2–4 reps early; over a few weeks the gap shrinks. (4) Re-test to failure about monthly as you get stronger.4
7Check yourself
What you can now say
- RIR 1–3 = RPE 7–9 — leave one to three reps in the tank.
- Beginners stop too early, underestimating reps left by ~4–5.
- The reliable cue is the bar slowing involuntarily, plus form drift and the "$100 test".
- Hypertrophy RIR 1–2; heavy compounds RIR 2–4; true failure rarely.
- Calibrate: meet failure once on a machine, then predict-and-check for a few weeks.
§References
- Helms et al. (2016). Application of the RIR-based RPE scale, Strength Cond J. PMC4961270. Scale origin: Zourdos et al. (2016), PubMed 26049792.
- Steele et al. (2017). Predicting reps to failure improves with experience, PeerJ. peerj.com/articles/4105.
- Emanuel, Halperin et al. (2020). "Just one more rep!" — even trained lifters underpredict, Front. Psychol. frontiersin.org.
- Stronger By Science — Reps In Reserve (calibration & velocity cues). strongerbyscience.com.
Lesson L7 of the dad-mod course · all lessons · glossary