An Ultra-Athlete’s Guide to RPE

An athlete’s rate of perceived exertion, or RPE, is one of the most underappreciated metrics. For ultra-athletes who are closely in touch with their bodies and minds, working with RPE is an essential component to training and racing.

An ultra-runner summits a mountain peak with the sun low in the sky behind him

I have an aversion to training by numbers. I prefer to utilize my innate sense of self to direct my training, believing that I have a fine-tuned understanding of what I need, what I don’t need, when to push, and when to rest. At this point, I train solely on feel, or RPE—rate of perceived exertion.

There are several RPE scales that athletes can use—the Borg scale being one of the most popular. All of them offer a standardized way to classify a subjective feeling, in this case the intensity level of physical activity. In essence, RPE is a score of how hard you feel like you’re working.

My confidence in RPE developed after many years of training, racing, and using data strategically. Importantly, there were also times when I kept myself blind to the data while my coach tracked my progress, and my perceptions were verified against the numbers. This led me to conclude that I could effectively train on feeling alone.

The importance of RPE can’t be overstated, whether you work with power and heart rate or not. In fact, Fast Talk has produced an entire episode on the importance of RPE, arguing that the metric of feeling is, in many ways, the most important metric.

Because of this, it’s critical to have a solid grasp of what RPE truly represents, its shortcomings and advantages, and how to effectively use it. This is true for any athlete, particularly ultra-endurance athletes who have a highly tuned sense of their physiology and, hopefully, psychology.

Calibrating perception

For the purposes of this discussion, I’ll assume you have some familiarity with both RPE and power and/or heart rate data—maybe you even have some physiological lab or field test data.

To reap the full benefits of RPE, it’s best to verify, or calibrate, your perception of your training ranges across the intensity spectrum (base, tempo, threshold, max effort, and so forth) to align the individuality and subjectivity of the RPE scale with any test numbers you have.

“Maybe the athlete says that the base ride they just did is a 4 [on a 1-10 scale],” says Ryan Kohler, founder of Rocky Mountain Devo coaching. “And it aligns with the heart rate data, but I’d normally say a base ride is a 2 or a 3. Still, I wouldn’t try to re-train someone and tell them, ‘That has to be a 3.’ I’d work with what makes sense for them.”

Consistency in the rating of perceived exertion is more important than the accuracy, or how appropriate the RPE corresponds to test data.

RELATED: The Power Ratings of Perceived Exertion

Beyond the calibration, Kohler also has athletes give a rating of how good or bad they feel during the effort. So while RPE is a rating of how hard an effort feels, this rating further describes how good or bad it felt.

“Put descriptors to those RPE numbers and also describe whether it remained stable or how things changed throughout the effort,” Kohler explains. “Things like, ‘my legs were spinning freely’ or ‘my legs were burning’ are what I’m looking for. This exercise will help you internalize the sensations even more.”

This second metric helps to create a more comprehensive illustration of the intensity of the effort. Somedays a threshold effort will feel like you’re floating. That will lead to one type of conversation. Other days, that same threshold effort will feel like you’re riding through molasses. That will lead to a very different conversation, with your coach or yourself.

Finally—and particularly if you are self-coached—it’s helpful to journal or record your RPE data, to keep you honest, consistent, and in tune with your perceptions over time. Without a coach to lend an outside perspective, it’s up to you to hold yourself accountable.

The advantages and disadvantages of RPE

Before the advent of the heart rate monitor, RPE was everything. But once new technology hit the market, people gravitated toward it and RPE lost its luster. Fast forward several decades and history repeated itself; this time, when power meters became prevalent, heart rate data was downplayed for power numbers, and RPE became an afterthought.

Nowadays, that sense of self is often foreign to athletes who focus solely on the numbers. That is to their detriment, as we have discussed many times on the Fast Talk podcast.

RPE underlies everything the numbers attempt to spell out; a solid grasp of RPE forms the foundation of successful training.

“Training by feel allows you to come into yourself more, to communicate with your body rather than have a device—be it power meter or HR monitor—tell you what you’re doing,” Kohler says.

On the flip side, if you don’t take the time to calibrate your sense of self, or you ignore the signs your body is sending you, relying solely on RPE can lead you astray—or, more accurately, it leads you to wander from the target without grasping how far you have strayed.

“If you’re unwilling to do the work, to learn what your body is telling you, to listen to it, then you’re riding blind,” Kohler says. “You can undertrain yourself, overtrain yourself. It’s like trying to hit a moving target because you don’t know where to go exactly.”

The fact that RPE is a subjective variable also makes it susceptible to the influences of everything from conditioning to mood to the realities of life. If you are solely relying on RPE to guide training, you (or your coach) must be careful to take into consideration those other factors as you decide the best course of action. Was it truly a bad workout today or has a bad boss got you down? Feeling sluggish because you’re on the verge of overtraining or has your newborn baby been keeping you awake at night? Context is critical.

“If you’re only using RPE, it’s not just part of the puzzle—it is the whole puzzle,” says ultra-cycling coach and athlete Kristen Legan. “If you have power, heart rate, or even speed data, you can parse out the bad days based on that other feedback. When you’re relying on feelings alone, sometimes it can be hard to separate life from training.”

Legan stresses the importance of the coach-athlete relationship when focusing on RPE. A coach often serves as a surrogate psychologist, and when analyzing RPE, it’s crucial to understand the full context of the athlete’s life, to ask for and interpret that continual feedback.

What RPE can’t do

While an RPE scale captures the difficulty of a workout while it’s happening, it doesn’t give an athlete a sense for how rested or ready they are to take on more work. Metrics like chronic training load rely on power data and Whoop’s recovery measure is a function of heart rate variability and sleep data. But with RPE, this needs to be captured using a different scale.

This scale can be simple and of your own creation: Consider using something like a traffic light system with its red, yellow, and green scheme. On a daily basis, rate your readiness on the following:

  • How your legs feel when walking up or down stairs
  • General sense of fatigue or freshness
  • Quality of sleep
  • Quality of nutrition
  • If you’re getting over an illness or feel one looming on the horizon
  • Mental status: Do you feel ready to push, or do you wish to stay in bed and read a book?
  • How you feel after the first 5-10 minutes into a workout

It seems like a lot to consider, but once you make a habit of tuning into these various sensations and giving daily ratings, you’ll become familiar with yourself and your needs, and be able to use it to make informed decisions for the day’s prescription. Feeling red? Back down. Yellow? Carefully consider the above ratings and make an assessment out on the road. Don’t be afraid to stop the workout if things deteriorate. Green? Go ahead and go!

Why RPE works for ultra-endurance athletes

As a generalization, ultra-athletes tend to spend a lot of time racing and training alone. Because of this, they are more likely to have frequent conversations with their bodies and be in tune with internal sensations.

RPE works best when an athlete has a solid grasp of both physical and psychological signs of performance. Experience also helps you anticipate what to expect during or after a given workout or training block. Ultimately, training and racing by feel works best for those with a refined sense of self.

“In ultra, you’re so connected internally for such a long duration—you’re constantly making assessments of when to eat, when to focus, when to push, when to relax, when to stop,” Kohler says. “RPE is everything.”