Your “maximum Heart Rate” Is Probably Incorrect
If you’ve ever worried about your heart rate getting too high or too low during exercise, you’ll want to read this. Your “heart rate zones” may be completely wrong. Not only are zones defined differently across different apps , but they’re usually calculated based on your maximum heart rate. And that maximum heart rate calculation? This is not true for large swathes of the population.
What does it mean to know your “maximum” heart rate?
Maximum heart rate, by definition, is the fastest rate your heart can beat. If your watch tells you that your maximum is 180 beats per minute, and then you go for a run and your heart beats at 190 beats per minute, you have not exceeded your maximum. You just discovered that 180 is not your maximum at all. Your actual maximum should be at least 190.
The only way to truly know your maximum heart rate is to test it through intense exercise. Below I will tell you several ways to do this. Fitness gadgets and apps (as well as books and other sources of fitness advice) try to skip this step by using a formula that estimates your maximum heart rate based on your age. The most popular formula simply subtracts your age from 220.
But there are problems with this formula and even with the alternative equations that have been proposed in its place. There is no formula that can tell you what your personal maximum heart rate actually is.
Why you shouldn’t trust maximum heart rate formulas
These formulas—no matter which one you choose—are universal calculations that will be approximately accurate for determining the average maximum heart rate of people of a certain age. But it doesn’t matter what the average is if you’re trying to determine the maximum heart rate for you as an individual.
Think about how you buy shoes. You don’t tell an app you’re 5’6″ and then trust it if it says the average 5’6″ person wears a size 8 shoe. You need to try on different shoes or at least measure your feet. Maybe you’re a size 6. Maybe you’re a size 9. It doesn’t really matter what size the average person wears because many people have larger or smaller feet than the average person.
The same goes for maximum heart rate. The idea of ”calculating” your maximum heart rate has become so common that people assume the calculation is correct, or at least very close to it. But take a look at this graph from a 2012 study in which researchers measured the actual maximum heart rates of more than 3,000 people. (The lines represent two supposedly more accurate maximum heart rate formulas.)
If you’ve ever wondered about your maximum heart rate, this will help you feel grounded. For example, I’m 44 years old, and the formula “220 minus your age” would lead me to believe that my maximum is 176. But with heavier workouts, my heart rate tends to reach 190, and I’ve gone over 200 several times with a chest strap ( most accurate measurement method). Looking at this graph, a heart rate of 200+ is certainly high for 44 year olds, but it’s unheard of and I wouldn’t even call it rare.
The same study also found that formulas become even more inaccurate as people age. Check out the averages they found for different age groups:
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Ages 19 to 29: 195 plus or minus 9.9.
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Ages 30 to 39: 189 plus or minus 10.1.
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Ages 40 to 45: 183 plus or minus 10.9.
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Ages 50 to 58: 176 plus or minus 11.6.
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Ages 60 to 69: 171 plus or minus 12.3.
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Age 70+: 164 plus or minus 12.4.
“Plus or minus” in this sense refers to the standard error, meaning that most people fall within this range, but by no means all . So even a formula that is supposed to find the average for a given age doesn’t take into account how people’s heart rates actually change as they age. For example, the entry for my age group indicated that my heart rate would likely be between 172 and 194 (instead of the standard prediction of 176). But I know that my maximum heart rate is 202.
And while I have a higher maximum heart rate than most people my age, there are also many people whose heart rates are lower than the formulas predict. Bottom line: Not only is there a wide range of norms, but general formulas are becoming less and less accurate in older adults. I don’t believe any heart rate calculation is accurate enough to set your personal zones or exercise goals.
How can the formula be so wrong?
The “220 minus age” formula was based on observations from sparse data, as detailed in this article on the history of the formula . The same article notes that all formulas developed since then have similarly poor error rates (plus or minus 10 beats per minute, and in many cases more – which is consistent with the 2012 study I mentioned above) . “There is currently no acceptable method for estimating maximum heart rate,” they wrote in 2002, and that remains true today.
I feel that I must say something here about the unknowability of the mysteries of the heart. (Surely some poet beat me to it.) The truth is that age alone does not determine a person’s maximum heart rate, so no matter what numbers you use to create an age formula, you simply won’t get a useful result. If there were other obvious relationships, such as if your weight or exercise habits affected your maximum, a more precise formula would undoubtedly be possible. But people differ in their maximum heart rate for reasons we don’t fully understand, just as they differ in shoe size, so it doesn’t seem like math can solve this problem.
Unfortunately, manufacturers of smartwatches and other devices want to have some default zones that will appear when you start using their products, even if you’ve never done a max effort sprint in your life. This is why we keep seeing these erroneous numbers over and over again. I can understand the dilemma of smartwatch manufacturers: on the one hand, only intense training will determine your real maximum. But on the other hand, most beginners will not want to take intensive tests and may not have enough experience to properly pace themselves and achieve their maximum in the test. People with cardiovascular, metabolic, or kidney disease should not engage in strenuous exercise without first consulting a doctor .
What should you do instead of relying on your maximum heart rate calculation?
Because of the above issues, reputable organizations have largely abandoned the idea of ”calculating” maximum heart rate. Runner’s World has removed the target heart rate calculator . The American Council on Exercise, one of the largest personal training certifying organizations, instructs trainers not to use maximum heart rate calculations , but to conduct real-life tests to help clients match their heart rate to the appropriate intensity of exercise. (I am ACE certified and can confirm that this is what the textbook says.)
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If you’re a beginner, you don’t need a heart rate target at all . If you can exercise without getting out of breath, you are in a good “zone” for steady-state exercise. You don’t need to think too much about it.
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If you want to evaluate this, you can do the Submaximal Speaking Test . An informal way is to simply notice what number you see on your watch when you can no longer speak comfortably; a more formal way is the treadmill test .
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If you really want to know your maximum heart rate, you can check it out . I would only recommend this to relatively experienced people, and would obviously skip it if a medical professional has ever advised you to stick to low-intensity exercise. Instructions are below.
How to check your maximum heart rate
First, I’ll tell you how you don’t find this: You don’t start cold and then try to run as hard as you can until you’re exhausted after 10 seconds. Your heart rate will jump, but in such a short time it will not approach the maximum value. It takes time for your heart to get up to speed, and once you really start pushing yourself, you’ll need to maintain that hard effort for at least a few minutes as you push harder and harder. With that in mind, here are a few different ways to determine your true maximum heart rate.
Warm up and then walk up the big hill three times.
Here is a common protocol, the most famous of which was described by Pete Pfitzinger in the book “Marathon for Advanced” :
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Jog for 10 to 15 minutes to warm up.
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Run hard up a moderately steep hill that is at least a quarter mile long (Pfitzinger recommends a 600-meter hill).
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Once you get to the top, run back down and repeat.
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After three repetitions, the test is over. The highest number recorded by your watch is your new high.
If you don’t have a smartwatch, you can take your heart rate with two fingers on your neck at the top of each hill rep. The highest number you see is your maximum.
Warm up and then do three four-minute intervals.
This test works similarly, but does not require a hill climb and does not need to be run. It comes from the Cardio Exercise Research Group at the Norwegian University of Science and Technology, the same group that popularized the Norwegian 4×4 workout. Here’s how they describe it :
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Warm up thoroughly (“to get you sweating,” as they say). A 10-15 minute warm up as above should help.
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Work hard for four minutes (running, cycling, etc.) and then give yourself three minutes of active recovery, such as brisk walking.
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Repeat the four-minute heavy interval again, followed by another three minutes of active recovery.
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Finally, begin another four-minute interval. This time, when you’ve walked for two minutes, run as hard as you can. Or as they put it: “increase your speed even more and run until you are too tired to continue.”
The highest number you see on the heart rate monitor (or, again, what you end up measuring manually) is your maximum.
If you are experienced, use the race to estimate your maximum heart rate.
You can probably skip field testing if you’ve done more than one race. But one word of caution: If you’re going to rely on this, it helps to have experience running races. If you set out to run a fast mile, but you run too hard in the beginning and slow down toward the end, your heart rate may never reach its true maximum. But if you run several runs at a good pace, you will see your heart rate at your highest at the end. (My own current high of 202 was seen twice: once at the end of a graded exercise test that pushed me harder and harder until I couldn’t continue; and once at the end of a 1-mile time trial that I was running along the path.)
If you start at a fast pace and then increase it a little as you go and finish in an extended sprint as you get closer to the finish line, you’ll likely hit your max or something pretty close to it. An FTP bike test or 5K run will often look like this, so if you’re an experienced runner or cyclist, you can probably just look at your heart rate during your last hard race and assume that number is higher. or less than your maximum.
Note that your maximum heart rate for running may be different from the maximum heart rate for other sports such as cycling and, most famously, swimming. Your heart has to work harder to pump blood when you’re upright rather than horizontal. If you determine your maximum heart rate using a running test and then use it to train in the pool, you’ll be chasing numbers that you can’t actually achieve in the pool.
However, heart rate metrics are only as good as the workouts they guide you to, so whether you should use heart rate percentages to guide your workouts depends on whether those math-guided workouts are helping you get faster, stronger, and healthier . If you work best without numbers, that’s fine; if you use numbers, make sure they are accurate.