RIR counts the reps you could still have done after a set; RPE rates the same effort on a scale up to 10. So RPE 8 means two reps in reserve.
What do RPE and RIR mean?
RPE stands for rate of perceived exertion. In strength training, the scale is tied to your reserve: 10 means no more reps were possible, 9 means one more, 8 means two more [1].
RIR stands for reps in reserve. It’s the same information, just as a number of reps: RPE = 10 − RIR.
| RPE | RIR | Meaning | In Tarvo |
|---|---|---|---|
| 10 | 0 | no more reps | 0 |
| 9 | 1 | one more | 1 |
| 8 | 2 | two more | 2 |
| 7 or less | 3 or more | three or more | 3+ |
How close to failure should I train?
For muscle growth, the closer to failure, the more growth. Going all the way to failure adds little on top [2, 3]. In one study, the thigh grew just as much with one to two reps in reserve as with training to failure [4].
So for most sets, one to three reps in reserve is enough. For strength, proximity to failure matters less; strength grew similarly across a wide range [3].
How accurately can I judge my reserve?
Roughly. On average, people underestimate their reserve by about one rep; they’re more accurate close to failure and at 12 reps or fewer [5]. Trained lifters on the bench press were off by 0.65 reps on average [6].
That’s why Tarvo doesn’t ask for RPE in half steps, but for 0, 1, 2 or 3+. Anything finer can’t be judged honestly.
What does Tarvo do with your answer?
After the last set of an exercise, Tarvo asks: how many more could you have done? Answering is optional and shapes your next session:
- 3+: The weight goes up now, even before you reach the top of the range, as long as no set fell short of its target.
- 1 or 2: Every completed set gets one more rep.
- 0: The target stays; you were at your limit. Only if you reached the top of the range does the weight still go up.
- No answer: same as 1 or 2, one more rep.
Progressing by effort works in studies: the squat improved more this way than with fixed percentages [7, 8].
Sources
- [1]Zourdos et al. (2016). Novel Resistance Training-Specific Rating of Perceived Exertion Scale Measuring Repetitions in Reserve. J Strength Cond Res. doi 10.1519/jsc.0000000000001049The RPE scale that rates effort by repetitions in reserve.
- [2]Refalo, Helms, Trexler, Hamilton, Fyfe (2023). Influence of Resistance Training Proximity-to-Failure on Skeletal Muscle Hypertrophy. Sports Med. doi 10.1007/s40279-022-01784-yMeta-analysis of 15 studies. Training to failure added little or no growth over stopping just short of it.
- [3]Robinson, Pelland, Remmert, Refalo, Jukic, Steele et al. (2024). Exploring the Dose-Response Relationship Between Estimated Resistance Training Proximity to Failure, Strength Gain, and Muscle Hypertrophy. Sports Med. doi 10.1007/s40279-024-02069-2Meta-regression. The closer to failure, the more growth; strength grew similarly across a wide range.
- [4]Refalo, Helms, Robinson, Hamilton, Fyfe (2024). Similar muscle hypertrophy following eight weeks of resistance training to momentary muscular failure or with repetitions-in-reserve. J Sports Sci. doi 10.1080/02640414.2024.2321021Study of 18 trained lifters. Training to failure and stopping one to two reps short grew the thigh equally.
- [5]Halperin et al. (2022). Accuracy in Predicting Repetitions to Task Failure in Resistance Exercise. Sports Med. doi 10.1007/s40279-021-01559-xReview of 12 studies, 414 people. On average they underestimated their reserve by about one rep, more accurately close to failure.
- [6]Refalo et al. (2024). Accuracy of Intraset Repetitions-in-Reserve Predictions During the Bench Press Exercise in Resistance-Trained Male and Female Subjects. J Strength Cond Res. doi 10.1519/jsc.0000000000004653Study of 24 trained lifters on the bench press. Their estimate was off by 0.65 reps on average.
- [7]Graham, Cleather (2021). Autoregulation by "Repetitions in Reserve" Leads to Greater Improvements in Strength Over a 12-Week Training Program Than Fixed Loading. J Strength Cond Res. doi 10.1519/jsc.000000000000316412-week study of 31 men. Progressing by reps in reserve raised the squat more than fixed percentages.
- [8]Larsen, Kristiansen, van den Tillaar (2021). Effects of subjective and objective autoregulation methods for intensity and volume on enhancing maximal strength during resistance-training interventions. PeerJ. doi 10.7717/peerj.10663Review of 14 studies. Progressing by effort (RIR, RPE) raised maximal strength.