Rating of Perceived Exertion

Rating of Perceived Exertion: Why You Should Use It Today

Okay, heart rate isn’t the best metric for tracking workout intensity.

Everyone is wrong from time to time, and now is one of those times for me.

About three years ago, I was initiated into the ‘Heart Rate Cult.’ It was a lovely time. They had cookies and punch.

I didn’t drink any punch.

The experience from using heart rate training lead me on the right path, though. And by consistently researching better training methods, I found the rating of perceived exertion.

But, before we get to that, let’s discuss heart rate training.

Why Did I Follow Heart Rate Training?

When I began running, I was young, energetic, and had no idea what I was doing to train properly.

But, I did what I always do when I don’t know something. I told everyone I was an expert in it and spoke as if I knew better than others.

Er, wait, no.

I researched! Yeah, that’s right. I began reading everything I could get my hands on about training.

Podcasts? Download them all and annoy my girlfriend with endless conversations about the same subject.

Articles? Bookmark, bookmark, annnnnnd bookmark.

Books? Not enough space in my phone’s storage for all of them.

Heart rate isn't the best tool for measuring intensity; rating of perceived exertion is.
Courtesy of Canva

I became infatuated with how to improve my training and, most of all, how to train properly. And that’s when I found heart rate training.

It sounded intuitive. Keep your efforts easy; you can exercise more often. I had been running myself into the ground in my training, so this sounded like a far better proposition.

And the theory behind it made sense to me. Exercise at a lower heart rate, and I’ll improve the systems used with that exercise. Raise my basement, raise my roof, right?

So, I started following it. It was hard at first. I had to run slowly. I was tempted to run faster, but I held off. There’s a reason behind this, I thought to myself.

But that didn’t make it any easier when ol’ Grandma Muriel came running past me, slapping me on the cheeks and telling me to pick it up.

Eventually, though, Grandma Muriel was in my dust. I saw increases in my endurance and overall speed.

But let me explain why I was wrong this entire time.

Why Heart Rate Training Isn’t the Best Tool

Many factors impact a person’s heart rate reading. This causes an inflated or deflated reading, which affects the information the athlete uses to make decisions about their training.

If this information is incorrect, it impacts the athlete’s entire training.

And our heart rates, especially when measured by a wrist heart rate monitor, can misrepresent an athlete’s intensity when running.

What Influences Your Heart Rate

As you increase and decrease your speed, your muscles demand more and less oxygen, respectively. Meanwhile, red blood cells are scrambling around like the Running of the Bulls to deliver oxygen to your muscles.

Therefore, your heart rate needs to increase to get more red blood cells to your muscles faster. And repeat.

A step-by-step process to how our muscles work
A rudimentary explanation, but simplicity is best.

If that were the only influence on your heart rate, then heart rate would be an excellent intensity measurement.

But it isn’t.

If you’ve lived a day as a functioning adult, you know there is a laundry list of things that increase your heart rate.

But here are a few that influence it related to running:

  • Body temperature
  • Stress
  • Altitude
  • Fatigue
  • Caffeine or other stimulants and depressants
  • Natural excitation or nervousness
  • Hydration status

Let’s look at an example.

In Phuket, Thailand, where I lived for the previous two years, the temperature was usually near 90 °F (32 °C). And the humidity was a solid 95-100% always.

The best time to run was in the morning before the sun would rise and turn everyone into tiny raisins. However, I opted to make the (un)wise decision and run later in the day when the sun was at its highest.

As I was driving to my run, a clown car’s worth of inputs were influencing my heart rate.

  1. The excitation that comes from the constant near-death experience of driving on Thai roads
  2. Stress that comes from the constant near-death experience of driving on Thai roads (it can be terrifying)
  3. An impossibly hot Sun beating down on my exposed body
  4. The coffee I drank an hour before leaving for my run

Beginning my run slow was normal for me. However, midway through my run, I’d be feeling fresh and ready to push my body a bit.

But, my Coros watch was telling me my heart rate was already higher than it should have been for the workout.

Rating of perceived exertion is a superior way of measuring intensity.
Courtesy of Canva

So, I’d back off, ignoring how I felt for what I was being told.

As a result, the workout lost effectiveness, and I went home with more in the tank than I should have.

For one workout, this may not be an issue. But, compound this across months of training, with workouts almost every day, and the changes could be massive.

But there is a solution.

👉 Want a free way to track your training?: An Intervals.icu Review: Free Software to Track Sports Data

Why Rating of Perceived Exertion (RPE) is a Better Tool

Let me start by clarifying I still use heart rate as a metric to track the intensity of my workouts. It’s a valuable tool if you know what influences it.

However, a case can be made the rating of perceived exertion (RPE) is a better indication.

If you’re unfamiliar with the rating of perceived exertion, it’s a system using a numbered scale (often 1-10) to measure the intensity of a workout according to how it felt to the athlete.

Measurements of 1-3 are inactive. 4-6 for easy-normal runs. 7-9 for hard workouts. And a 10 is an all-out effort where you crawl into the fetal position and ask for a warm milk bottle at the end.

The rating of perceived exertion is an athlete’s subjective analysis of how the workout intensity felt for them. No biometrics, no readings, just how you felt.

Rating of perceived exertion scale

This may sound ridiculous, but there’s evidence to back up its use in evaluating our internal training load or our body’s response to a training session.

Jason Koop, a lead ultrarunning coach and author of Training Essentials for Ultrarunning, uses RPE with his athletes.

Even though his athletes have access to the top fitness gear and measurement tools available, he still opts for the rating of perceived exertion over every other advanced metric available.

He explained, “When you are scrambling up a 25 percent grade in a cold thunderstorm at 10,000 feet above sea level, 65 miles into a 100-mile ultramarathon, what heart rate would define lactate threshold pace? What minute-per-mile pace should a midpack ultrarunner aim for in that scenario?”

His answer may be tongue-in-cheek, but he hits a crucial point. How do you measure the intensity level runners should aim for that accounts for all scenarios and factors? Heart rate, pace, and other measurements currently miss the mark.

RPE is the only measurement that accurately captures a runner’s state and intensity.


So, look at me now. I am a recovered heart rate cultist in the flesh and ready to admit my mistakes.

All jokes aside, this is the beautiful aspect of training; we’re all constantly learning. We try things; they may work, but they may not. But, we adapt and continue experimenting.

As I move on with my training, I am happy I followed heart rate training initially because it began to set me in the right direction.

It’s essential to keep researching and updating our knowledge to improve our training methods, and the best way to do that is to listen to the experts.

So, what mistakes have you made in your training have you learned from? And what do you currently use to track your workout intensity?

Side note: If you’d like to purchase Coach Jason Koop’s book “Training Essentials for Ultrarunning,” you can find it on Amazon using the link below. The book is a fantastic addition to your library if you enjoy running and finding ways to improve. Don’t let the title steer you off if you don’t run ultras; the advice in this book is for runners of all kinds. I strongly recommend buying it.

Click the image below to buy Training Essentials for Ultrarunning on Amazon.

Science of Ultrarunning

Disclaimer: The image above contains an affiliate link. By using this link, I earn a small commission. You’re not charged a higher price nor required to use these links. It only helps me out a bit. Thanks.

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3 thoughts on “Rating of Perceived Exertion: Why You Should Use It Today”

  1. Im not convinced about this. The reassons you list for heart rate being potentially elevated ( heat, stress etc.) all boil down to one thing. Stress. And isnt the whole point of the low hear rate training to prevent you from putting too much stress in the system, which changes how energy is used snd fat is metabolised?

    1. Thanks for your question, Pete. It’s an excellent one.

      You’re correct on some points.

      However, there are some issues with heart rate training. To start, our bodies don’t automatically switch to burning fat once we hit X heart rate. That’s one of the follies I’ve found with heart rate training is that you believe you’re in this zone, so you’re optimizing a certain system. But, that’s not necessarily the case.

      And, besides, we can still optimize these same systems using RPE.

      As well, if your heart rate was a direct indicator of the work your body was doing during a workout, then heart rate training would be perfect. But, it’s not, it’s a subsidiary indication.

      That’s why your heart rate being elevated or depressed due to outside influences is an issue. You may think you’re doing more work because your heart rate is high, but it may not be that way for your muscles, which leaves performance gains on the trail or causes you to overexert yourself due to a lower heart rate reading.

      And that’s assuming that the heart rate data you’re getting is accurate. With the factors mentioned above, plus the known issues of the heart rate monitors we have currently, how sure can you be that you’re getting an accurate reading?

      I don’t think heart rate is useless, it helped me a lot in my training. And I still use it in my training, it’s just not my primary measurement.

      I’m interested to continue hearing your thoughts on this.


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