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How to Estimate Proximity to Failure Through Effective Use of RPE Scales

Prevailing wisdom suggests that training to failure is necessary for optimizing training outcomes (muscle growth, strength gain, etc.).


The idea is that only by pushing yourself to your true limits, can you cause a significant enough disruption that shakes up homeostasis and promotes adaptations.


But as training practices and research develop, we’ve come to understand that such methods might not be necessary. In fact, they could be counterproductive, especially for recreational athletes.


Read on to learn about proximity to failure and why using an RPE scale to track your effort could be a much better approach.

What is RPE?

Short for rate of perceived exertion, RPE is a numerical scale designed for trainees to track their training efforts during weight training.


RPE scores are subjective and largely based on how you’re feeling at the end of a set. You can more accurately determine your rate of perceived exertion by taking into account your breathing, heart rate, and how tired your muscles are.


The early version of the RPE scale was developed to measure the fatigue level of marathoners. It was called the Borg Rating of Perceived Exertion Scale, named after the Swedish scientist who created it: Gunnar Borg.


The Borg scale ranged from 6 to 20, with 6 corresponding to no exertion and 20 meaning maximal effort. Here is a more in-depth look:


The Borg Rate of Perceived Exertion Scale
Rate Perceived Exertion
6 No exertion
7 Barely any effort and fatigue

Very light




Somewhat challenging




Highly challenging

19 Near-maximal effort
20 Maximal effort


In case you’re wondering why the scale goes from 6 to 20 instead of, say, 1 to 10, it is because each value loosely corresponds to a specific heart rate. More specifically, multiplying each value by ten would give you a rough estimate of your heart rate, which is an excellent indicator of cardiovascular exertion.


For example, if you’re cycling on a stationary bike and your session feels light, your heart rate will likely be between 100 and 120 beats per minute.


As time passed and we had some research on heart rate variability, Borg decided to revamp his scale, which led him to develop the Modified RPE Scale that goes from 1 to 10.

The Most Common RPE Scale Used Today

Unlike the 6-20 scale, the modified version is much easier to understand and apply. It isn’t based on heart rate but still aims to help high-level athletes manage their fatigue, at least in the context of aerobic exercise.


Borg’s modified RPE scale goes from 1 to 10 and is the foundation of the scale athletes can use to build strength and gain muscle.


Similar to his original scale, the new one measures subjective feelings of fatigue, where 1 means barely any exertion and 10 corresponds to extreme fatigue and an impossibility of doing more work.


It wasn’t long until someone took Borg’s scale and modified it further to fit trainees in the context of weightlifting. That person was Mike Tuchscherer, an IPF world champion powerlifter and a renowned powerlifting coach.


He first introduced his version of the RPE scale in his book, The Reactive Training Manual, where the rate of perceived exertion is determined based on how many more repetitions a trainee believes they could have done.


RPE Scale Based on Repetitions In Reserve (RIR)

Very light training; barely any effort.


Could get 4 to 6 more reps.

7 Could do 3 more reps
7.5 Could definitely do 2 more reps, maybe even 3.
8 Could do 2 more reps.
8.5 Could definitely do 1 more rep, maybe even 2.
9 Could do 1 more rep.
9.5 Couldn’t do more reps, but maybe lift slightly more weight.
10 Couldn’t do more reps or use a heavier load.


As you can see, the scale is also based on subjective feelings of fatigue, which means it takes experience to use effectively. We will discuss that aspect of RPE in the following points.

The Correct Mindset Toward RPE Scales

RPE might seem a bit abstract, which could be why some trainees are reluctant to use it in their training. But as discussed in earlier points, the objective of RPE is to track your training effort, which leads to better fatigue management.


In other words, RPE is a tool you should add to your toolbox to improve your training. It doesn’t have to be complex and shouldn’t feel overwhelming to use. As with most things, practice makes perfect.


Using RPE becomes particularly important for more advanced trainees who need to learn fatigue management if they hope to progress. It’s one thing to recover from five sets with 135 lbs on the bar and a whole other to do the same after squatting 600+ lbs.


Progression slows to a crawl for intermediate and advanced athletes who have moved beyond their newbie gains. The weight often becomes much heavier than their body weight, so the training stress is larger and needs to be managed more effectively.

Putting RPE’s Subjectivity Into Objective Numbers


RPE tracking and fatigue management became quite popular after Dr. Mike came up with the RPE-to-Reps table:


As you can see, this is far more actionable and can be a great starting point for people who don’t have the experience to rely on subjective factors when estimating their RPE.


The table is quite helpful and does a great job of estimating how many reps you should be able to do at a specific percentage of your 1 RM. In addition, it includes RPE figures to guide you further and help you determine your effort level.


Using the table for up to 12 reps per set is best. Anything higher than that becomes too difficult to track accurately.


If you’re struggling to estimate your maximum strength and put these numbers into practice, you can use one of the many available formulas. An example is Boyd Epley’s:


(0.033 × Number of repetitions × Weight) + Weight


Let’s say that you can bench press 135 reps for 15 reps. The equation would look like so:


(0.033 x 15 x 135) + 135 = 201.8 lbs


In other words, given the reps and weight, the formula estimates your 1RM to be 202 lbs for that movement. If calculations aren’t your thing, you can use an online calculator that does it for you.

Why Athletes Should Utilize RPE In Their Training Routine

Old, dogmatic ideas suggest athletes should push themselves to their limits to optimize progression. But as research and practical experience develop, we’ve come to understand that fatigue management is a crucial piece of the puzzle.


Maintaining a submaximal intensity, aiming for an RPE of 7 to 9, is generally ideal for everyday fitness enthusiasts. Such effort levels are enough to cause a significant training stimulus without leading to excessive fatigue or putting athletes at risk of injuries. As a result, supercompensation is more likely to occur, leading to optimal progression.


Research also supports this line of thinking. For example, in one recent review of the literature, researchers sought to determine the effectiveness of RPE during resistance exercise. The authors considered 118 studies and included 75 of them in their meta-analysis.


Here’s what the authors concluded:


“RPE provides a valid measure of exercise intensity and physiological exertion during resistance exercise, with effect sizes comparable to or greater than those shown during aerobic exercise. Therefore, RPE may provide an easily accessible means of prescribing and monitoring resistance exercise training.”


Of course, these findings don’t paint a complete picture because, as discussed, RPE relies on subjective feelings, and trainees need experience to apply the scale in their training.


For example, in one paper, researchers examined perceived exertion and self-selected training loads and how these differ when the participants are told what training to do. The subjects were 19 untrained women.


According to the paper’s findings, the participants couldn’t accurately measure their effort level or train at a high enough intensity to stimulate meaningful strength and hypertrophy improvements.

The Benefits of Using RPE In a Training Routine

Tracking RPE is a simple but profound habit that elevates training performance, leading to better results.


Athletes using RPE often report that the scale helps them autoregulate their progress and make their training more purposeful. As a result, they are less likely to lose motivation due to fears of becoming overtrained.


In addition, research shows that RPE tracking is a fantastic way to manage training efforts and limit fatigue accumulation.


For these reasons, many powerlifters, bodybuilders, and everyday gym-goers leverage RPE to manage their training plan. Regardless of the workout approach, RPE is a scale that works as intended, so long as trainees put effort into learning to gauge their level of exertion.


In essence, the RPE scale provides a simple and practical way to gauge the difficulty of each set, allowing athletes to auto-regulate their efforts and avoid overtraining. Doing so makes it easier to integrate an effective fitness plan into a person’s life without causing it to affect productivity or subjective well-being.

How Beginners Can Leverage RPE Principles

As discussed above, the RPE scale works excellently for trainees of all levels. Beginners might struggle to use the scale, but there are ways to work around any roadblocks that might present themselves.


Newbie lifters who aren’t good at measuring their RPE could utilize the principle of monitoring proximity to failure on every set by using a slightly different method. One option is the reps in reserve (RIR) scale, similar to RPE but limited to 5 instead of 10 points.


Another option is a facial rating system of 10. Though it may sound strange, the approach seems superior to RIR. Research suggests the approach is more intuitive for the average person who may not be familiar with terminologies such as RPE or RIR.


The Strongineering framework recommends a bodybuilding RIR scale and a facial rating system of 10 for novice lifters.

Strongineering’s Recommended Best Practices For RPE

Before diving into the practical recommendations, it’s important to reiterate that the RPE scales and Facial Rating System of 10 are largely subjective. Trainees must evaluate themselves and determine their exertion level accurately, which largely stems from their perception and how the particular training day is going. In other words, it isn’t always 100 percent accurate, although it will largely accurate if you are doing typical resistance training around 1-12 repetition ranges.


It’s also important to note that adopting the RPE scales in a training plan requires dedication and deliberate practice. Athletes must monitor perceived fatigue after each set while sticking closely to their well-structured workout plan. Like other small things, doing so isn’t that challenging but requires discipline and the will to do what is necessary, regardless of how you feel.


Women usually rate their sets with a higher RPE than men. We saw such effects in one of the studies reviewed above. Another study, where researchers compare perceived fatigue levels between men and women, shows similar results.


Here’s a great resource that looks more closely at these differences and potential causes:


Sex-Related Differences in Ratings of Perceived Exertion and Estimated Time Limit


Despite having the same RPE scale for the two biological sexes, Strongineering recommends that females push themselves a bit more––say, 0.5 points on their RPE. If a set feels like an RPE of 8, they could perceive it as 7.5.


In contrast, some men might consider overestimating their efforts slightly to manage their effort and fatigue. If a set feels like an RPE 8, they could log it as RPE 8.5.


To minimize any adverse effects due to limitations, Strongineering alters the recommended load (percentage of 1RM), the repetitions, and the number of sets per exercise. Any such changes depend on the athlete’s self-report or completion of a questionnaire related to the training day.


Based on the athlete’s feedback and considering additional information like their mood, energy levels, and sleep quality, the Strongineering framework will adjust each workout to assign the appropriate intensity and volume.

The Advantages of Building Your Custom RPE

The Strongineering framework recommends that experienced and elite lifters build their custom RPE-to-Reps table for their training. It should be based on their previous training data and account for past performances and recorded RPEs.


There is a significant variance between how athletes perceive fatigue, which depends on anatomy, leverages, cardiovascular capacity, body composition, body weight, fiber type distribution, and more. As such, two athletes with similar training histories might interpret the same training set differently. One might see it as an RPE 10 (0 RIR), whereas the second might rate it 7 or 8.


Every athlete should make some minor adjustments to the RPE-to-Reps table we shared above.


One helpful option is for athletes to use certain common benchmarks, such as their 1RM, 5RM, and 10RM, on specific exercises to establish anchor points. Doing so would provide a foundation for each athlete’s table, and the remaining sections can be filled up by referring to the changes imposed in the standard RPE-to-Reps table.


It’s worth reiterating that previous records of top sets (RPEs of 9 and 10) are crucial in making a reliable RPE-to-Reps table. Lower effort sets can also be useful but leaving 2, 3, or even 4+ reps in the tank makes it difficult to determine your actual RPE.


Finally, we recommend that athletes change their RPE-to-Reps table every time they finish a training program (e.g., every 3 to 6 months). Refining the table as you go is a great way to make it more accurate and leverage RPE better. Still, you should avoid making frequent alterations because day-to-day performance fluctuations are expected, and you might make too many unnecessary changes.