You may have heard me say that you should do a particular exercise at a particular intensity or your doctor may have told you to get 150 minutes of moderate to vigorous intensity exercise per week. Do you need to buy an activity tracker or get a kinesiology degree to know exactly how intense these workouts should be? The truth is that you probably already innately know how hard you are exercising. It’s called Rating of Perceived Exertion (RPE) and it’s already installed in your brain!
Way back in the nineteen hundred and eighties, when we would put on our polyester short shorts, striped knee-high sports socks, terry towel head and wristbands, and go out for what was then called a jog, we didn’t have an activity tracker on our phone, a GPS on our wrist, or a heart rate monitor in our hat (which really does exist, by the way). We would simply go out for an easy, moderate, or hard run. And we still managed to not only be fit but we also managed to qualify for things like the commonwealth games, the Boston Marathon and the olympics. I know! I’m shocked as well.
So, how on earth did we ever manage to qualify for these high-level events when we didn’t know our splits (an event or workouts’ total time divided into smaller parts ), our current pace, or our heart rate zone? Well, unless you were fancy enough to have a coach with a stopwatch and a heart rate monitor on a golf cart (honestly, Dr. Phil Maffetone tells stories of doing this back in the day), you used Perceived Exertion (PE).
What is Perceived Exertion?
Perceived Exertion is simply how hard you feel that your body is working at any given point during a workout.
This includes things like heart rate, respiration, sweating, muscle fatigue, and much more. You know, all the delightfully exillerating physical sensations that we experience during a workout.
Using these factors to determine the amount of exertion you feel is a good estimate of your measurable variables such as heart rate (how many times your heart beats per minute) and lactate threshold (at what level of exertion your body manufactures lactic acids faster than it can flush it).
Can Perceived Exertion Be Quantified?
I know what you are probably thinking: “Sure, Brock. That is fine if you aren’t that serious but for my training program, I need the accuracy of a watch that can measure down to the square meter.” Well, I am here to tell you that you probably don’t. Your own sense of your exertion is nearly as accurate as using the latest tech. The trick is to have a scale to judge it by. That is where Swedish researcher Gunnar Borg comes in.
The Borg Scale
Dr. Gunnar Borg invented what he called the Borg Scale which matches how hard you feel you are working with numbers between six and 20. Yes, I know it seems weird to start at six but I will explain that later.
The scale begins at “no feeling of exertion” (which is equal to six) and tops out at “very, very hard” (which is equal to 20). Pretty simple, right? The moderate activities fall between “fairly light” (or 11) to “somewhat hard” (or 14) on the scale. More vigorous activities equal 15 or higher which is labelled as “hard,” “very hard,” or “very, very hard.”
Now, back to the number six thing. This is the cool part. Dr. Borg set the scale to start at six because, if used correctly, the scale would become an easy way to estimate heart rate. If you multiply your Borg score by ten, it gives you an approximate heart rate for a particular level of activity. As crazy as that sounds, it has been tested time and again and proven to be not only useful but also very accurate.
Is the Borg Scale Accurate?
Back in 1973, the American College of Sports Medicine did a study titled The validity and reliability of a rating scale of perceived exertion where they used Borg Rating Scale.
They took eight lean and eight obese subjects and tested whether they could perceive small differences in work intensity even when the workloads were presented in a random order. The results were compared with the results they had obtained during an earlier progressive exercise test.
They tested each subject twice and the testing order of the two protocols and also the order of workloads used during the random tests were assigned using a Latin square design. In the end, there were no significant differences in any of the physiological and perceptual variables between the two types of test protocols. Coefficients of reliability for both procedures were high.
In 2013, there was a cohort study done in the European Journal of Applied Physiology called Associations between Borg’s rating of perceived exertion and physiological measures of exercise intensity where they evaluated the association between Borg’s RPE and physiological exercise parameters in a very large population.
2,560 Caucasian men and women (no non-white participants but at least they included women this time… yeesh) between 17 and 44 years old completed incremental exercise tests on treadmills or stationary bikes. Their heart rate, blood lactate concentration, and Rate of Perceived Exertion (RPE) were all simultaneously measured. Rating of perceived exertion was strongly correlated with heart rate and blood lactate. They concluded that “Borg’s RPE seems to be an affordable, practical and valid tool for monitoring and prescribing exercise intensity, independent of gender, age, exercise modality, physical activity level and Coronary Artery Disease status.”
As you can see, the correlation of performance versus perceived exertion during physical activity has been and continues to be an area of considerable scientific interest. The idea that although exertion is unique to every individual, it can still be used as a subjective estimate of the work intensity across a variety of populations is an important one. The intensity at which we all exercise is important because of the risks of things like musculoskeletal injuries or potential disorders arising from mismatching an athlete’s capability and the physical demands of their workout.
Like I always say, we need to avoid the “too much, too soon” issue at all costs and monitoring your RPE is a helpful tool to have in your injury-proof toolkit.
How To Use the RPE Scale
Ok. Now something actionable!
Starting tomorrow, when you exercise, instead of staring at your Fitbit, Apple Watch, or Garmin, you need to start rating your own exertion. You can rate it in your head if you like, you don’t need to write it down or do anything fancy. After all, this needs to become automatic and ingrained if it is going to work.
This feeling of exertion should combine all sensations of physical stress, effort, and fatigue including how hard it is to breathe, how much your muscles are burning, how badly you want to stop the workout, and how in control you feel of your body, and even changes in your vision and hearing.
Once you have spent some time thinking about that and becoming more aware of how your body feels at different levels of exertion, you need to determine how your RPE scores line up with a particular training pace or workout type.
For new exercisers, this may take some time, but for you experienced athletes out there here is an estimate of some common workouts and their Borg score rating.
- Recovery run = 7 to 8
- Long Slow Distance run = 9 to 12
- Tempo Run (Half to Marathon race pace) = 13 to 14
- Threshold Run (10K to 10 Mile race pace) = 15 to 16
- VO2 max (3K to 5K race pace) = 17-18
- Max effort (1 Mile to 3K race pace) = 19-20
So, when you start applying this scale to your running, a comfortable run should feel like a nine or 10. A run where you just let yourself go at a “comfortably uncomfortable” pace might be more like a 15 or 16. Then an 800m interval or a hill repeat would be more like a 17 or 18.
What about 20, you ask? Well, picture the final kilometre of a 10K race where you have been truly giving it your all. Or perhaps the last 400m loop of a track, when your legs are turning to jelly and your lungs are on fire. Or that time when you told your parents you would be home before 10 and you are still a few blocks from home at 9:58 and you are trying to maintain an all-out sprint to avoid getting grounded… again. Yeah, that’s a 20.
Why Do I Need This?
Have you ever arrived at the pool or park and realized you forgot your activity tracker at home? Or perhaps you have it but the battery is at 1%? Maybe you want to do a quality workout while you are on a vacation or on a business trip and you don’t have any of your tech with you. Or you are at the gym and you know that gym treadmills, rowing machines, elliptical trainers and step machines are notoriously poorly calibrated. Or perhaps, you just don’t want to (or are unable to) shell out the dough for yet another piece of gear. Isn’t it good to know that your own internal heart rate monitor and GPS are functioning just as well as that $500 watch you were nearly pressured into buying?
If you are someone who has been coached by me, you will know that I generally give my client athletes a “nature workout” at least every two weeks. This is important for two reasons:
- Sometimes we are so hung up on hitting our paces, numbers, steps, or heart rates that we forget to enjoy the fact that we are out in the sunshine, rain, snow or whatever.
- It is really good for your nervous system to unplug occasionally. This goes double for us wired fitness folks.
As Emmy-award-winning chief medical correspondent for CNN and practicing neurosurgeon Sanjay Gupta told Oprah: “Sometimes it’s better to ignore the stats and listen to your body instead. You’ll probably feel calmer if you just give yourself a chance to unplug.” I couldn’t agree more.