Exercise Intensity: How Good Are You at Judging How Hard You’re Exercising?

Exercise Intensity: How Good Are You at Judging How Hard You’re Exercising?

(Last Updated On: March 31, 2019)

Exercise Intensity: How Good Are You at Judging How Hard You’re Exercising?

Are you a good judge of how hard you’re exercising? According to a new study carried about by Canadian researchers, many people overestimate how hard they’re working out. In other words, they think they’re working harder than they actually are. Sometimes it’s hard to judge exercise intensity without the benefit of a heart rate monitor. If you’re like most people, you have days when your workout feels easy and other days it’s a challenge to get through it.

 Are You Exercising as Hard as You Think?

In this study, researchers asked a group of 129 young and middle-aged volunteers to walk or jog on a treadmill for three minutes at various intensities – light, moderate and high-intensity. The participants self-selected the pace they thought corresponded with each level of exercise intensity from light to vigorous. During the treadmill jog, researchers measured their heart rates. Then researchers asked the participants to walk at the minimal pace they felt would qualify as moderate-intensity exercise.

The results? The participants were pretty accurate at judging when they were exercising at a light pace. However, they weren’t so good at judging moderate and high-intensity exercise. In most cases, they overestimated their exercise intensity and didn’t meet the criteria for moderate or high-intensity exercise based on their heart rate. Moderate-intensity exercise corresponded to a heart rate of 65% of maximal heart rate and vigorous exercise 75% of maximal heart rate. In this study, middle-aged participants were better judges of how hard they were working than younger ones.

What does this mean? Some people overestimate how hard they’re exercising. As a result, many may not be achieving a heart rate level sufficient for cardiovascular conditioning. As a result, some well-meaning exercisers aren’t getting the full benefits exercise offers. Underestimation of workout intensity is more likely to be a problem for people who are new to working out, less so for “old pros” that work out every day. Still, it calls into question how good the average person is at judging how hard they’re exercising.

Measuring Workout Intensity

The most accurate way to measure exercise intensity is with a heart rate monitor. Although not entirely accurate, you can, for simplicity, calculate your estimated maximal heart rate by subtracting your age from 220. Using this formula, the number you calculate may be off as much as 10 to 20 beats per minute. This formula tends to overestimate maximal heart rate in people over the age of 40. A more accurate, but still not perfect formula is 211 minus 64% of your age. For example, a 30-year-old has an approximate maximal heart rate of 211 – 30(.64) or 192.

Now that you know your maximal heart rate, you can determine how hard you’re working based on the percentage of maximal heart rate you’re exercising at. For moderate-intensity exercise, your heart rate should be between 65% and 75% of your calculated maximum. For vigorous exercise, 75% to 90% of your maximal heart rate is the target range.

A heart rate monitor gives you constant feedback you can use to judge your exercise intensity. Using a heart rate monitor takes the guesswork out of how hard you’re working. As a result, you can make appropriate changes to your intensity based on your fitness goals and level of fitness. When you’re starting out, stay at the lower end of the range until you’re better conditioned.

Alternatives to a Heart Rate Monitor

You can also manually check your heart rate during a workout. To do this, count your pulse rate for 10 seconds and multiply by 6. It’s less convenient than wearing a heart rate monitor but it works. Another way to measure exercise intensity without a heart rate monitor is using the Karvonen Formula. This formula uses your maximum calculated heart rate and resting heart rate to determine your target heart rate. The formula looks like this:

(MHR – RHR) x Intensity) + RHR = target heart rate

MHR = maximal heart rate

RHR = resting heart rate

Intensity – based on what percentage of your maximal heart rate you want to work out at

If you wanted to work out at a high-intensity, you might choose 80% of your maximal heart rate or 0.80 as your intensity. To simplify things, there are online calculators you can use to get your target heart rate.

Even Simpler Ways to Estimate Exercise Intensity

You can use the Borg scale to estimate how hard you’re working. The Borg system is based on a scale of 6 to 20 with 6 being no exertion and 20 being maximal exertion. When you’re working out you would estimate your perceived exertion using numbers. For example, 11 is light activity, 13 is somewhat hard, 15 is hard, 17 is very hard and 19 is barely tolerable. Moderate-intensity exercise would be in the 12 to 14 range. Research shows the Borg scale gives a pretty good estimate of how hard you’re exercising. If you multiply your perceived exertion on the Borg scale, it also roughly correlates with exercise heart rate. For example, if you estimate you’re working at a “15” level on the Borg scale, your heart rate should be roughly 15 x 10 or 150.

Even simpler is the “talk test.” This simple test gives you a rough gauge of how intensely you’re exercising. If you’re working out at a moderate-intensity, you should be able to talk in complete sentences but not sing. When you’re working out at a high intensity, it should be hard to say a whole sentence without taking in a breath.

The Bottom Line

If you’re serious about getting fitter, having a way to judge how hard you’re working is a good idea. Many people underestimate their level of exertion during exercise. Whether you choose a heart rate monitor or a simpler method like the talk test, use a method to track and monitor your workout intensity.



PLOS One. “Individuals Underestimate Moderate and Vigorous Intensity Physical Activity”

IDEA Health and Fitness Association. “Comparing Intensity-Monitoring Methods”

Scand J Med Sci Sports. 2013 Dec;23(6):697-704.

Centers for Disease Control and Prevention. “Perceived Exertion (Borg Rating of Perceived Exertion Scale)”


Related Articles By Cathe:

How Do You Know if You’re Working Out Hard Enough?

4 Benefits of Wearing a Heart Rate Monitor During Exercise

Using Maximal Heart Rate to Measure Exercise Intensity – Is the Formula Flawed?

Endurance Exercise Adaptations: 6 Things That Exercise Increases

How the Heart Rate Response to Exercise Changes With Age

How Accurate Is Maximum Heart Rate for Measuring Exercise Intensity?


2 thoughts on “Exercise Intensity: How Good Are You at Judging How Hard You’re Exercising?

  1. Hi Cathe,

    “When you’re working out at a high intensity, it should be to say a whole sentence without taking in a breath.”

    I think you meant to write, “it should be hard to say…” (see sentence directly above heading “the bottom line).

    Great article. In some of your older step videos we did perceived exertion test and I think your earliest ones had us take a 10 sec pulse check between routines. I know The Firm (the Anna Benson years) used the pulse check. I never quite “got” perceived exertion because it seemed subjective. However, in your videos you explained that we should be able to speak but not sing a song. That helped because I tried to sing along with some of the great songs in the video.

    I appreciate the article. I don’t have a heart monitor and have always used the percentage of maximum heart rate to monitor my exertion. I knew it wasn’t the most accurate method but it was a good gauge. I might give some of the other ones you mentioned a try.

    Again, great article. The website and newsletter have become a good resource of information. Kudos to everyone involved.


    Fitness Friend,

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