Reps in reserve
Also known as: RIR
Reps in reserve (RIR) is an estimate of how many more complete repetitions a person could have performed before reaching the chosen failure point. Zero RIR means no additional repetition was possible; two RIR means the set ended with an estimated two repetitions still available.
RIR describes training effort, not the weight itself. For example, eight squat repetitions at 70% of 1RM might leave four RIR early in a training cycle but only two RIR on a fatigued day. The training intensity is unchanged, while the effort differs. RIR can therefore help prescribe and compare sets without requiring an all-out repetition test every session.
The endpoint must be defined for the estimate to mean anything. In most training contexts, count only repetitions that could be completed through the intended range of motion with the agreed technique. Zero RIR at technical failure may occur before true momentary muscular failure because the lifter could perhaps move the load only by shortening the range or changing the movement. Exercise selection also matters: estimating one more controlled machine repetition is not the same task as judging another heavy free-weight repetition.
RIR is subjective. Lifters can underestimate or overestimate what remains, especially when sets are stopped far from failure or the movement is unfamiliar. A systematic review and meta-analysis found that prediction error varies with factors such as proximity to failure, training status, and the way the test is performed. Calibration can improve by using consistent technique criteria, recording the estimate immediately, and occasionally comparing it with a safely performed high-effort set. That does not make every future estimate exact.
There is no universal RIR target for every exercise, set, and goal. Evidence summarized in a meta-analysis on proximity to failure suggests that hypertrophy may tend to increase as sets terminate closer to failure, but it does not establish one precise cutoff that everyone must reach. The expected benefit, added fatigue, technique demands, and consequences of a failed repetition all affect a sensible choice.
Alpha Progression Pro supports RIR as an optional plan or workout setting. When enabled, an RIR target can be assigned to each working set and the completed value can be entered in half steps, such as 1.5 RIR. Generated plans can include RIR targets, and periodized plans can vary them from week to week.
RIR is not required for Alpha Progression’s progression recommendations. The app can recommend a weight and repetition target from logged performance without an RIR entry. When RIR is enabled, the recommendation can also include a set-specific RIR target. The user can still edit the value or disable RIR for the plan or current workout.