RPE vs. RIR: What’s the Difference?

RPE and RIR are both methods of autoregulating training variables, whether that be load, number of sets, or number of repetitions performed, for the purpose of improving training performance and managing fatigue. RPE stands for Rate of Perceived Exertion, while RIR stands for Reps in Reserve.

I’ve written about RPE in detail before – if you haven’t yet read that article, you should definitely check it out before moving forward with this reading.

Though both methods revolve around the same concept and thus yield fairly similar results, I don’t always use them in the same way with my clients and in my own training.

In this article, I hope to shed some light on the distinction between the two, which will help you pick the best tool for the job as needed.

RPE – Rate of Perceived Exertion

As mentioned previously, there’s a whole article dedicated entirely to RPE, so I won’t go into much detail here. Suffice to say, RPE is best used when loads are fairly heavy (close to one’s 1RM), repetitions are low, and the lifter has a pretty good gauge on their training performance, especially when dealing with heavier weights.

RPE allows you to adjust your load selection based on your training readiness that day.

That means, if you’re feeling particularly beat up, you may choose to go 10 or 15 lbs lighter than you had initially predicted.

Similarly, if you’re well-rested, full of vigor and ready to smash some weights, a 5-10 lb jump may be more appropriate for that day’s training.

Though the scale ranges from 0 to 10, sub-6 RPEs are considered too light to provide a significant training effect. RPE 10 sets, on the other hand, represent a maximal effort set, which typically equates to your repetition-max at any given weight.

(Credit to reactivetrainingsystems.com)

RIR – Reps in Reserve

The Reps in Reserve method offers virtually the same benefits as RPE, albeit with a slight advantage.

Instead of rating your performance, the RIR value indicates exactly how many “reps in reserve”, that is, how many repetitions should be left in the tank during a particular exercise.

This makes for a far more intuitive approach to autoregulated training, which is specially beneficial for beginners and less experienced trainees.

When we talk about reps left “in the tank”, we’re talking about how many repetitions you’re capable of doing BEFORE your technique breaks down.

Say you’re performing sets of 8-12 reps on back squats, and your program calls for 2 RIR on each set. At a given weight, you may find that you can easily hit 10 reps on your first set, with 2 reps left in the tank. As the sets progress and fatigue kicks in, your number of repetitions achieved may decrease – and that’s okay, so long as you stay within the given intensity range (that is, 2 reps short of failure) and within the target repetition range (in this case, 8 to 12 reps for that specific exercise).

RPE vs RIR: The Main Differences

One of the benefits of using RIR over RPE is that you can apply it to a much wider rep range.

Accurately gauging the RPE for a high-rep set is nearly impossible, as you can almost always do at least ONE more rep when loads are light enough.

For that reason, RPE is best suited for strength lifts. That is, it’ll give you the most precise feedback when the goal is expression of maximal or near-maximal strength, as is the case in powerlifting.

RIR, on the other hand, may be best suited for ‘accessory’ type work, such as lifts geared towards muscle hypertrophy or muscular endurance.

But there’s another distinction between the two – and it’s the one thing that confuses my clients the most.

When using RPE, we’re gauging our proximity to muscular failure – that is, the point at which our target muscles are no longer able to exert enough force to overcome the resistance.

In contrast, RIR-training caps off working sets at the point of technical failure, that is, the point at which your technique significantly breaks down. Think of it as using too much body English during bicep curls, rounding your back in a deadlift, or letting your knees cave in excessively in a squat.

Technical failure ALWAYS precedes muscular failure, which is why you’re still able to move weight even when your technique is no longer optimal.

Does That Mean Technique is Less Important When Using RPE?

No. Both RPE and RIR methods assume your technique is being held to a certain standard.

Let me explain.

In a perfect world, all reps would look the same – regardless of how much weight is on the bar. 

Advanced trainees certainly experience less form breakdown as their loads go up – this is a skill that’s sharpened by showing up without an ego and being willing to prioritize technique over load.

But the reality is, for a lot of us fitness junkies, some technical breakdown is to be expected as we approach our strength limits.

Regardless of where you fit within that spectrum, the point we need to keep in mind is that moving weight “at any cost” isn’t a sign of strength progress.

The true sign of mastery comes when you start moving increasingly heavier weights with the exact same technique you use when pushing sub-maximal loads.

In fact, that’s something we should prioritize if our goal is to keep lifting optimally and pain-free when we’re well into our 70s.

But the main distinction here is PERCEIVED EFFORT. RPE is a measure of effort, not difficulty, within a given set. It tells you how hard you worked, in relation to your maximal ability.

RIR, on the other hand, keeps you more honest with regards to technique. This is incredibly useful as it allows us to practice and ingrain correct movement patterns, while still pushing for a desired training effect.

A Few Things to Keep In Mind…

RPE and RIR are both extremely valuable tools, but there are some limitations.

The most glaring drawback of using these methods, specifically when it comes to untrained or novice lifters, is the trainee’s ability to accurately gauge RPE or RIR.

Here’s the thing: performance awareness and proficiency with self-monitoring techniques improve as a lifter gains training experience.

There is no way around it – more experienced lifters will have a much easier time understanding and evaluating their performance.

However, that doesn’t mean beginners can’t benefit from learning and applying autoregulation techniques.

In fact, I would strongly encourage any beginner lifter to start implementing these methods early on in their training, even if it’s in conjunction with a percentage-based programs (as an example), to gain a deeper understanding of the methodology and its application over time.

One of the main criticisms of using autoregulatory techniques with novices is that they often underestimate their strength limits, and for that reason, consistently undertrain by leaving more reps in reserve than necessary.

In reality, this isn’t something that significantly impacts their results.

Yes, it’s true that beginners routinely underestimate their strength performance.

However, beginners also don’t need to train close to failure, at least not in the same frequency as more intermediate and advanced trainees.

Training to failure is a great way to stimulate more motor units and to really push the limits of strength development, but it also creates more room for errors in technique.

The goal of training, at its early stages, should be to develop enough proficiency within the movements so that intensity can be then scaled up accordingly.

A lot of beginners make the mistake of putting the carriage before the horse and pushing for maximal loads when their technique isn’t quite able to sustain itself at near-maximal loads. Don’t make that mistake. Perfect your technique first, then learn how to gradually up the intensity so that you can truly develop your strength potential.

To your strength,

Coach Barbara


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About The Author

Barbara M.

Since 2013, Barbara has helped women of all fitness backgrounds get stronger, leaner and more confident, both inside and outside the gym.

Her passion lies in educating, empowering and encouraging women to find out what they’re capable of, and more.

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