Reps in Reserve (RIR) Explained

Reps in Reserve (RIR) is a tool for autoregulating training intensity by estimating how many reps you have left before failure. This guide explains how to use RIR for strength, hypertrophy, and power while integrating velocity-based training for a complete approach.

By Travis Mash

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Introduction

In high performance strength training, guesswork is not enough. Athletes need precise tools to adjust effort, manage fatigue, and train with intent. Reps in Reserve, or RIR, is a simple yet powerful method that helps fine tune training intensity in real time. This article explores what RIR is, how it compares to RPE, and how combining it with velocity based training can reduce subjectivity and improve performance.

What is Reps in Reserve (RIR)?

Reps in Reserve is similar to Rate of Perceived Exertion (RPE). It’s the number of extra reps you believe you could do before hitting muscular failure, or more simply before you can’t do another rep with proper form. For example, if you’re doing a bench press and you think, “I could do two more reps,” that’s 2 RIR. It’s subjective, but when an athlete gets better at understanding their true intent during training, it becomes a useful tool for autoregulation.

Why does it work? Because your brain and muscles communicate. When you tune into how your body feels, you can adjust your effort on the fly based on your perception of fatigue or feeling fresh or overly fatigued. At that point, you’re training smart and staying in the optimal zone for hypertrophy, strength, or power depending on the daily goal. Fatigue levels change day to day due to various internal and external factors;. Autoregulation has become  non-negotiable. The coach’s goal is to ensure the athlete isn’t going too hard, and on the other hand, the coach must ensure the athlete is going hard enough to stimulate the intended response.

How Reps in Reserve (RIR) Works in Performance and Programming

Different goals require different RIR targets:

  • Hypertrophy: 0-4 RIR. You want enough fatigue to stimulate muscle growth but not so much that you’re grinding to failure.
  • Strength: 1-2 RIR. Push close to the limit, but leave some reps in the tank to recover faster and lift more consistently.
  • Power/Speed: Very few reps to failure and in this zone, velocity is king. You focus on moving the bar fast and leaving some in reserve. This is where RIR and RPE can fall short.

Over time, athletes and coaches master estimating RIR, and then training becomes more personalized. You’re not blindly following numbers, but instead, you’re listening to your body, adjusting effort, and avoiding the pitfalls of overtraining or injury. Using RIR creates flexibility and awareness, which we are learning is key to long-term progress.

How Reps in Reserve (RIR) Works in Performance and Programming

Reps in Reserve (RIR) for Hypertrophy

If you read my article discussing “The Size Principle”, you will see that hypertrophy requires maximum effort or intent of the athlete and a slow enough velocity to maximize myosin and actin cross-bridges. Therefore, a level of fatigue must be present to slow the barbell or machine down enough to aid in that process. An athlete must also consider the total volume of those fatigued reps and the frequency of performing those repetitions in a week. 

Therefore, it’s ok to take things to a zero RIR, but you must consider the body’s ability to recover. Staying between 2-4 RIR for the majority of the time is probably a safer route to ensure recovery and therefore frequency. Don’t be afraid to take things to 0-1 RIR maybe once during the session especially on the single joint accessory movements. For specifics on how many sets and reps for hypertrophy, click here. To dive deeper into hypertrophy, check out Muscle Hypertrophy: Theory to Application.

Reps in Reserve (RIR) for Strength

The biggest difference between hypertrophy and strength when it comes to RIR is the need for massive amounts of force production. Once again, that’s in my article The Size Principle. Force happens at the lowest possible velocities, so 0-2 RIR’s are required to maximize force production. The speed of the barbell actually determines the adaptation, which I explain clearly in this article The Adaptation is in the Speed. Strength relies on the relationship between the muscular system and the nervous system along with the connective tissue. Let’s just call it, the neuromuscular system must practice at those low RIR’s and low velocities to perfect the efficiency of the neuromuscular system including the tendons that resist stretch and transfer force. Check out how many reps and sets to gain strength.

Reps in Reserve (RIR) for Power/ Speed

Here’s where RIR and RPE fall short the most. Let’s be practical now. The closer we get to failure makes it easier to predict the number of repetitions left in reserve. Whether we are performing 60% of our 1RM for 15 repetitions or 85% for 5 repetitions, that last rep feels similar. 

However, if I want to maximize an athlete’s power output that happens around 65-70% of their 1RM for several sets of 3 repetitions, that’s going to happen at around a triple with about eight repetitions in reserve. No one is going to guess that one with any amount of accuracy. If you want to refer to the chart below, you will be able to see how intensity, RIR, RPE, and velocity all work together.

Reps in reserve (RIR) relative intensity chart

Comparing Reps in Reserve (RIR) to Rate of Perceived Exertion (RPE)

Now, a lot of folks use RPE, Rate of Perceived Exertion, which we talked about last time. RPE is how hard everything feels—effort, pain, fatigue—all bundled into one subjective number. RIR, on the other hand, pinpoints how many reps you have left in the tank. Some people have started putting RPE and RIR together, but you can read about that in my RPE Article.

Both are subjective, and both are valuable. RIR tends to be more specific. It tells you how close you are to failure. RPE captures the overall effort, which may include psychological factors. Think of RPE as the fire lit under your effort, while RIR is how close you are to burning out.

In practice, using both together can give you a more complete picture. When RIR is low, RPE will likely be high indicating you’re pushing hard. The key is in understanding how to listen to your body and adjust accordingly.

As a coach of high level athletes and as a sport scientist that likes to perform my own research, I’m not a huge fan of either. Subjectivity can be the difference in winning and losing. In the case of research, my athletes and my readers are counting on my work to guide them along with their own goals and dreams. Subjectivity has little place in my world. Hence, I like to use VBT to measure my athletes regarding their fatigue levels and effort.

Integrating Reps in Reserve with Velocity (VBT)

Let’s look at a few ways of combining RIR with velocity-based training. Why? Because velocity offers an objective measure, hard data, and VBT confirms what you feel. Eventually an athlete will start to understand his or her intent being utilized into the barbell.

If you look at the chart I built for all of you, you can see how it all works together. A 1-2 RIR is going to correspond to the same relative velocity no matter how many total repetitions one is performing. If I am doing a back squat at a 5 repetition set at 2 RIR or a 3 repetition set at 2 RIR, that final repetition is going to come in at .37m/s to .4m/s because it will be nearing failure. The back squat has a minimum velocity threshold of around ~.3m/s, so a maximum effort set has to be nearing that failure velocity.

Practical tools include setting velocity thresholds, watching the bar’s speed in real time, and adjusting loads accordingly. This gives you a clear, immediate gauge allowing for no guesswork. You’re watching the data, not just relying on perception. You can use the velocity trend to estimate the Reps In Reserve (RIR), also known as reps left in the tank or reps until failure. If you are performing high velocity sets to improve power, I would rather tell you to perform a three repetition set with a velocity of .7m/s in the first 1-2 reps versus telling you to work up to a three repetition set at 10 RIR.

Velocity Loss

Another way of using VBT to teach intent is with velocity loss. Let’s say that you want your athletes to complete sets of 10 reps at 4 RIR. The first repetition will happen around .77m/s and will end around .425m/s. That’s a velocity loss of 45%, and that’s where hypertrophy is maximized. Velocity loss can be anywhere from 25-60% to elicit solid hypertrophy gains. Once again, velocity loss of 50-60% will also create the most fatigue.

Travis-Mash-Estimated-velocity-zones-data

Practical Application and Program Design

For Hypertrophy

For Strength

  • Aim for 1-2 RIR 
  • No matter what repetition range you are working with each set, the final velocity will be around .37m/s or less in the squat, .25m/s or less in the bench or deadlift, and .31m/s in the overhead press
  • with velocity data confirming you’re moving heavy weights efficiently. For example:
    • A 10RM Squat should start with a velocity of 0.7m/s in the first 1-3 reps and ending with .37m/s
    • Velocity loss of 48%
    • Percentage of 1RM ~67.5%

For Power and Speed

  • For power and speed, prioritize velocity 

Monitor progress by seeing how your velocity data correlates with perceived effort. Adjust loads based on the combination. if velocity drops more than expected at a certain RIR, back off slightly next session. The goal is to monitor fatigue and maximize performance.

Conclusion

When you combine RIR, the subjective measure of fatigue or how you feel, with velocity, the objective data from tools like GymAware RS or FLEX that shows how you are actually performing, you create a powerful system of autoregulation. This combination helps maximize adaptation while minimizing unnecessary fatigue. Over time, your athletes will develop a better understanding of the intent behind each rep and how to apply it consistently. GymAware RS and FLEX are simply tools that remove the guesswork and sharpen intent.

References

  1. Halperin I, Malleron T, Har-Nir I, Androulakis-Korakakis P, Wolf M, Fisher J, Steele J. Accuracy in Predicting Repetitions to Task Failure in Resistance Exercise: A Scoping Review and Exploratory Meta-analysis. Sports Med. 2022 Feb;52(2):377-390. doi: 10.1007/s40279-021-01559-x. Epub 2021 Sep 20. PMID: 34542869.
  2. Morán-Navarro R, Martínez-Cava A, Sánchez-Medina L, Mora-Rodríguez R, González-Badillo JJ, Pallarés JG. Movement Velocity as a Measure of Level of Effort During Resistance Exercise. J Strength Cond Res. 2019 Jun;33(6):1496-1504. doi: 10.1519/JSC.0000000000002017. PMID: 29944141.
Coach Travis Mash

Travis Mash

Being a World Champion in powerlifting, Travis competed at a world-class level in Olympic weightlifting and has coached professional Olympic weightlifters alongside Don McCauley and Glenn Pendlay at Team MDUSA. Now Travis coaches the most successful weightlifting team in the USA.