In this guide we explain what reps in reserve (RIR) is, how it compares to RPE, why it beats rigid percentages for strength training, and how it makes your rehab safer and more effective too.
What Is Reps in Reserve?
RIR is simply how many more reps you could have done before hitting failure on a set. If you finish a set and feel you had three good reps left, that is 3 RIR. It is a quick, honest gauge of how hard a set really was, and it puts you in control of your effort rather than a rigid number on a spreadsheet.
How the RIR Scale Works
The scale is intuitive. 0 RIR means you could not have done another rep, that is true failure. 1 to 2 RIR means very hard but with a little left. 3 to 4 RIR is challenging but comfortably short of failure, which is where a lot of productive training lives. The higher the number, the further from failure you are. Most quality strength training sits somewhere in the 1 to 4 RIR range depending on your goal.
RIR vs RPE
You may have heard of RPE, or rate of perceived exertion, a 1 to 10 effort scale. RIR and RPE are two sides of the same coin: an RPE of 8 usually means about 2 RIR, RPE 9 means 1 RIR, and RPE 10 is failure. Some people find RIR easier to picture because it asks a concrete question, how many reps could I still do, rather than rating a feeling. Use whichever clicks for you.
Why It Beats Fixed Percentages
Traditional programs prescribe a percentage of your one-rep max, but your strength changes day to day with sleep, stress, food and fatigue. A weight that is a hard triple one day might be easy the next. RIR accounts for this: you adjust the load to hit the target effort on the day, rather than forcing a number that no longer fits. This makes your strength training more consistent and far less likely to lead to burnout or injury, one of the reasons coaches love it for long-term strength training.
Using RIR in Rehab
It is just as useful in rehab. After an injury, loading the tissue is essential, but too much too soon flares things up. RIR gives you and your physiotherapist a simple dial: early on we might keep well away from failure, at say 4 to 5 RIR, then gradually push closer as the tissue tolerates more. It lets your rehab progress safely, guided by how you respond rather than a fixed program that ignores your day-to-day.
How to Use RIR in Your Training
Putting it into practice is easy. For each working set, aim for a target RIR based on your goal, lower for strength and size, higher for technique or early rehab. Be honest with yourself: if the bar slowed to a crawl, you were closer to failure than you think. Over time you get better at judging it, and your strength training becomes more responsive, sustainable and effective.
Common Questions About Reps in Reserve
What does RIR mean?
RIR stands for reps in reserve, the number of reps you could still do at the end of a set before reaching failure. It is a simple way to measure how hard a set was.
How do I know my RIR?
Ask yourself at the end of a set how many more good reps you could have managed. It takes practice, and bar speed is a good clue, the more it slows, the fewer reps you have left.
What’s the difference between RIR and RPE?
They measure the same thing differently. RPE rates effort from 1 to 10; RIR counts reps left in the tank. RPE 8 is roughly 2 RIR, RPE 10 is failure. Pick whichever feels more natural.
Is RIR good for beginners?
Yes, though it takes a little practice to judge accurately. Beginners often underestimate how many reps they have left, so erring toward a higher RIR early on is sensible and safe.
How does it help in rehab?
It lets you load an injured area by feel, staying well short of failure early and progressing as you tolerate more. A physiotherapist can use RIR to guide your rehab safely.
How BeFit Can Help
At BeFit Training Physiotherapy, we use tools like reps in reserve to make your training and rehab smarter. Our strength and conditioning coaching helps you apply RIR to your strength training effectively, and our performance physiotherapy and general physiotherapy teams use it to progress your rehab safely. Initial consultations run for 45 minutes, one-on-one.
Our team at Edgecliff and Coogee would be glad to help. No referral is required, and HICAPS is available on-site for immediate health fund claiming.
Book an appointment at BeFit Training Physiotherapy — no referral needed.
Edgecliff: (02) 9327 7749 | Coogee: (02) 7205 2805 | befittrainingphysio.com/book-now
Related Services at BeFit
Learn more about how our team can help:
Strength & Conditioning
Performance Physiotherapy
General Physiotherapy
Further Reading
The Truth About Training With a Physiotherapist
References
Zourdos MC, et al. Novel resistance training-specific rating of perceived exertion scale measuring repetitions in reserve. J Strength Cond Res. 2016.
Helms ER, et al. Application of the repetitions in reserve-based rating of perceived exertion scale for resistance training. Strength Cond J. 2016.
Australian Physiotherapy Association. Clinical guidelines. physiotherapy.asn.au.
