How to use reps in reserve

Reps in reserve, usually written RIR, estimates how many additional controlled repetitions you believe you could perform when a set ends. If you stop a set of eight squats and think two comparable reps remained, record 2 RIR. If you could not complete another repetition with the intended range, that is 0 RIR. RIR describes proximity to the end of a set, not a fixed load or a promise about the next session.

Use a simple scale

Use 0 RIR for no further controlled rep available, 1 RIR for about one more, 2 RIR for about two, and so on. The word “about” matters. RIR is a subjective estimate. A deadlift and bench-press study published in 2022 found repeatable load selection at 1 RIR in a small sample of young novice men. That is a narrow finding, not proof that every estimate is exact. A 2024 scoping review found RIR contextually useful and noted that prediction tends to be more accurate closer to the end of a possible set. Most participants across the reviewed literature were men, which limits broad generalization.

Keep the exercise standard steady. A push-up stopped because the hands slid is not a useful effort estimate. A set that ends because a timer rang is also different from a set stopped at 2 RIR. In the log, write both the performed reps and RIR: “row, 10 kg, 10 reps, 2 RIR.”

Example: use RIR with a rep range

Suppose your target is three sets of 8 to 12 rows. You perform 10 reps at 3 RIR, 10 reps at 2 RIR, and 9 reps at 2 RIR. The rep count alone says 29 total reps. The RIR notes explain that the first set was further from the perceived limit than the final two. At the next session, you might aim for one additional rep in the first set while retaining the same load and rest.

Do not calculate RIR from a chart of percentages. Estimate it from the actual set, then compare estimates over repeated sessions. If you frequently write 3 RIR but later discover you could do many more repetitions, revise the next load or range gradually. The goal is a useful personal record, not proving that your estimate is exact.

Avoid treating RIR as a command to fail

RIR can help you stop before the last possible repetition. It does not require testing failure to validate every set. Nor does a prescription of 2 RIR mean each exercise and session must feel identical. Equipment setup, sleep, and the movement itself can change the estimate. Keep your definition consistent: comparable repetitions with the intended range and control.

The research links above concern specific exercises and participant groups, so do not treat them as a universal conversion table. Use RIR alongside the basic record of load, reps, and rest. Over time, the estimate becomes more informative because it is attached to familiar exercises performed under known conditions.