Pain isn’t the only factor we need to account for when assessing a patient’s ability to assess their exercise capacity. The training history (type of activity, total volume, and typical intensity), age, gender, goals, motivations, and injury history can all play a role. The use of RIR differs as well. The previous study blinded participants to the load. What if you are training independently or a patient is completing a home exercise program? This meta-analysis investigated the RIR prediction accuracy estimates across multiple studies of differing populations and conditions. It assessed the following variables: training status, timing of prediction, repetition range (indicative of relative load), set number, and upper or lower body exercise.
The final analysis included 13 studies and 414 participants. On average, participants underpredicted RIR by roughly 1 repetition (0.95 mean). The 95% confidence intervals ranged from 0.17 to 1.73 which indicated in most cases, participants are within 2 reps. The training history did not matter, suggesting that a familiarization period may be enough for acceptable accuracy. The closer the participant was to failure, the more accurate the rating. For example, if you select a weight and guess 10 reps, you will find after 7 reps that you can do another 6, meaning your initial RIR was off by 3. The accuracy progressively deteriorated in sets greater than 12 repetitions. Accuracy may be better for upper body exercises but the results differences were trivial. If we consider the data from both studies presented, it appears RIR is an effective strategy for determining resistance training load provided a familiarization period was conducted and the sets are 12 reps or less.