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Introduction to RPE/RIR
RPE/RIR is one of the most commonly used terms in today’s strength culture.
RPE stands for Rating of Perceived Exertion and is a measurement of how
hard training is. Mike Tuchscherer originally adapted RPE for strength training
to incorporate Repetitions In Reserve (RIR).
RPE
Description
10
Could not do any more repetitions
9.5
Could maybe do 1 more repetition
9
Could do 1 more repetition (1 RIR)
8.5
Could do 1 more repetition, chance at 2
8
Could do 2 more repetitions (2 RIR)
7.5
Could do 2 more repetitions, chance at 3
7
Could do 3 more repetitions (3 RIR)
6.5
Could do 3 more repetitions, chance at 4
6
Could do 4 more repetitions (4 RIR)
1-5.5
This scale continues
The Rating of Perceived Exertion (RPE) scale based on Repetitions in Reserve (RIR)
In practice, RPE/RIR has served as a tool for lifters to adjust training based on
their daily performance. Load can be adjusted by the lifter within the training
session to achieve the desired number of repetitions at the desired RPE/RIR.
This within-session adjustment is termed autoregulation.
In addition to being a practical tool for autoregulation, RPE/RIR provides a
quantification of how close to failure a set is terminated. In this guide, we will
use the RPE/RIR scale to frame the discussion of “how close to failure should
our training be for maximizing increases in muscle strength and size?”
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Commonly Proposed Model
To answer the question of how close to failure we should train, a few models
have been proposed. One such model that has gained traction is what we’ll
call the “threshold model”.
The “threshold model”
This model suggests that “effective” training occurs only in the range of 0-4
RIR or 6-10 RPE. While this may be a decent practical recommendation at
times, our interpretation of the research leads us to different conclusions. Our
view is that there is sufficient research indicating that lifters can train outside
the 0-4 RIR range and still experience gains in strength and size. Further,
there may even be times - primarily for strength - when training with >4 RIR is
advised.
Perhaps more importantly, the threshold model takes options off the table. In
our coaching experience, we’ve observed that some lifters cannot accumulate
sufficient training workloads while only training in the RPE 6-10 range. We’ve
found that reducing average RPE can unlock progress for these individuals.
The mentioned factors have led us to propose a more open-ended model.
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Our proposed RPE/RIR model
Our proposed model doesn’t differentiate effectiveness between RPE ranges.
This might seem unhelpful at first, but we’ll give more specific models for
each strength and hypertrophy in a bit.
At this point, things might seem a bit paradoxical. On one hand, we think
appropriate RPE/RIR is an extremely overlooked aspect to program design
and individualization - heck, we’re writing a guide on it. On the other hand,
we can’t offer an RPE/RIR range that’s “optimal.” That’s the point, though: a
wide range of RPE/RIR can be effective.
Our goal in the rest of this guide is to provide the conceptual framework so
you can decide for yourself what RPE range makes the most sense based on
the goal of the set (i.e., strength or hypertrophy), the overall context of the
programming, and the lifter’s response to training. Let’s start with strength.
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RPE/RIR for Strength
Before we dive into RPE/RIR considerations for strength, it’s important to take
a step back and think through the characteristics of maximum strength. A
1RM is a test of maximal force production at a slow velocity. Next, we need to
consider why a 1RM is slow - this is of course because a 1RM load is heavy for
the individual.
This is opposed to a repetition being slow in a multi-rep set during training.
These reps slow down due to the fatigue accumulated from the reps that
have already been performed in the set. Since the barbell cannot be
accelerated to the same degree as fatigue accumulates, force production also
decreases. The below figure is relevant to volume work, in which the load
utilized is typically ~70-85%. Importantly, this concept of force production
decline is at a given load. Heavier loads will generally lead to higher force
production: greater force is required on the first rep and force can only drop
off so much before failing with heavier loads.
Specificity during a multi-rep set at a given load through the lens of force production
When you are performing a multi-rep set to failure, your ability to produce
force decreases as you fatigue within the set. Therefore, through the lens of
force production, the slow reps at the end of a multi-rep set to failure are
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actually less specific to a 1RM. Thus, the routes at which a 1RM and the last
reps in a set to failure become slow are different.
Rep Type
Velocity
Mechanism
Force Production
1 Rep Max
Slow
Due to the load being heavy
High
Reps late in a
multi-rep set
Slow
Due to fatigue
accumulated with the set
Lower
Why repetition velocity and force production don’t always align
Specificity through the lens of force production essentially flips the
“threshold” model on its head - it suggests the reps early in a multi-rep set are
actually the most beneficial for strength. We do subscribe to this line of
thinking, but there are some important caveats. While force production is a
vital aspect of 1RM specificity, specificity is multifactorial. The reps later in a
multi-rep set provide practice with movement variability; that is, practice
“grinding” through reps and shifting the loading demands to other muscles.
There are benefits to reps earlier and later in multi-rep sets
Thus, if you only perform lower RPE sets, you’ll lack practice with movement
variability. However, when top sets (i.e., 1-5 reps at RPE 6-10) are included in a
program, this will be taken care of. Further, the movement variability
exposure you get from these top sets will be due to the load being heavy as
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opposed to fatigue within a set, which is more specific to a 1RM. Heavy top
sets in combination with volume work in the 70-85% range that avoids large
within-set drop offs in force production is an excellent formula for “checking
your boxes” for strength with a high degree of specificity.
Ultimately, practical outcomes - actual increases in strength - are what we
care about. To that end, our research team authored a meta-regression of all
studies comparing different RPEs/RIRs. The outcomes of the analysis support
the outlined force production model of strength development as there was
no relationship between RPE/RIR and strength gains. Importantly, we only
included studies that were load equated. Thus, the below figure
demonstrates that at a given load, training closer to failure does not lead to
greater strength gains in the research.
Training closer to failure does not independently drive strength gains
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RPE/RIR for Hypertrophy
Hypertrophy is a different training goal, and the mentioned force production
reasoning doesn’t necessarily apply. Thus, we do see a general relationship
between proximity to failure and size gains in the meta-regression..
Training closer to failure does (at least in part) drive hypertrophy gains
Importantly, there were less studies in the hypertrophy analysis: 26 vs. 55
studies for strength). Further, while a linear relationship provided the best fit
of the available data, this was not overwhelmingly so. In other words, it may
very well be that the relationship is non-linear, either in the sense that the
stimulus accelerates or decelerates as failure approaches.
So, the mentioned “threshold model” in which all training is at 4 RIR or less is
likely a good starting point for most hypertrophy training. Further, training
closer to failure may be necessary to maximize muscle growth for synergistic
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muscles as well as in all regions of the target muscle, but more research is
needed to answer this question.
With that said, it’s important to note that the load used likely mediates the
degree to which proximity to failure drives hypertrophy gains. With heavier
loads, we generally see a less dramatic relationship whereas we generally see
a more dramatic relationship with lower loads.
This information can be helpful for strength athletes in which a lot of training
is performed with heavy loads. As an example, let's examine 21 total reps
being completed at 80% of 1RM via two different protocols:
1. 3 sets of 7 reps @ 1 RIR
2. 7 sets of 3 reps @ 5 RIR
Protocol #2 is an example of how you can set up training that violates the
threshold model but will almost certainly lead to meaningful muscle growth.
Further, an advantage to protocol #2 is that many find this to be less fatiguing
than protocol #1, so more total volume, higher frequencies, and/or heavier
loads may be handled throughout the week.
Practical Applications
First and foremost, we hope you now have more programming options on the
table than if you were to follow the threshold model. For instance, if you’re a
powerlifter and experience disproportionate fatigue with sets to or close to
failure, you may want to explore lower RPE protocols. In our coaching
experience, we often find that this change can allow lifters like this to
accumulate the necessary volume to progress. On the other hand, if you’re
training further from failure and haven’t experienced satisfactory hypertrophy
progress, you may want to dedicate more of your training to or very close to
failure, especially on “hypertrophy-friendly” movements like leg press,
dumbbell bench press, and Romanian deadlifts.
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For strength athletes in general, we’d suggest reconsidering how volume
work is designed. As mentioned, practicing with heavy weights is a vital
aspect of any solid strength program, but the configuration of the volume
work is where things can get tricky. Instead of performing multiple sets very
close to failure, consider breaking up the same amount of total repetitions
into more sets. This will lead to less bar speed reduction, which means there
will be more total force production, ultimately maximizing this aspect of
specificity for the volume work.
For those with body composition related goals (physique athletes and
strength athletes far from competition), there are also more options on the
table. With sufficiently heavy loads (>80% of 1RM), training to or very close to
failure does not seem to be required for effective hypertrophy training.
However, in practice, we still bias lower RIRs when muscle growth is the
primary goal. As mentioned, there is some uncertainty as to whether the reps
closer to failure are more stimulative for hypertrophy compared to the reps
farther from failure. We like to think about this as a cost-benefit analysis. If
there isn’t a massive fatigue cost to training close to failure, it probably makes
sense to accumulate your volume that way (taking your bicep curls to RPE
8-10 probably will not dramatically reduce the total volume you can tolerate).
If there is a disproportionate fatigue cost to training close to failure for a
certain exercise, then exploring lower RPE options may be warranted. In our
coaching experience, whether or not an exercise has a disproportionate
fatigue cost will vary from individual to individual, so some tinkering may be
required here.
We hope this guide stimulated some thought on how to best conceptualize
RPE/RIR, and most importantly, we hope you have some new tools in your
toolbelt!
- This RPE guide was created by Zac Robinson and Josh Pelland For the science-y version with all the data publicly available, visit this page.
For coaching/programming from the Data Driven Strength team, please visit
www.data-drivenstrength.com
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