After a set, a lifter writes “two repetitions in reserve.” That means they estimate they could have completed two more repetitions under the intended conditions. It does not prove that exactly two successful repetitions remained.
In Steele and colleagues’ study in PeerJ on predicting repetitions to momentary failure, predictions were not perfectly accurate, with training experience affecting accuracy. A study result does not turn every person’s estimate into a precise measurement. RIR is best understood as information about perceived remaining capacity.
Make the estimate comparable
Record the exercise, load, completed repetitions, and relevant technique standard alongside RIR. “Two more” means little if the imagined extra repetitions use a shorter range of movement or a different form from the completed set.
For an illustrative log, write “eight controlled repetitions, estimated three remaining” rather than only “easy.” Over several sessions, discuss patterns with a qualified coach. A sudden change may reflect sleep, fatigue, technique, or other circumstances rather than a simple increase or decrease in strength.
Do not deliberately attempt an unsafe extra repetition just to prove an estimate. Exercise selection, equipment, supervision, and individual health affect what is appropriate. Pain, dizziness, or other concerning symptoms should not be treated as a challenge to complete the predicted count.
Beginners may need time to learn what different effort levels feel like. Keep the language honest: “estimated” leaves room for uncertainty and useful adjustment. A training plan should account for that uncertainty instead of assuming that every recorded number is exact.
The value of RIR is a clearer conversation about effort. Used consistently with the rest of the session record, it can describe how a set felt without reducing the entire workout to the weight on the bar.