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Should you track your heart rate during workouts?

When this metric can be useful—and when just getting your pulse pounding is enough.

A woman checking her heart rate on a fitness tracker. Credit: Getty Images / Nastasic

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With fitness trackers and smartwatches keeping track of your pulse throughout the day, you may have gathered that heart rate could be a valuable health metric to keep tabs on. But what does it mean to train by heart rate? What’s “BPM”? And how does this all affect your health?

For some people, heart rate is just another data point to skim over. It can also be used to make your workouts more effective. We talked to experts to find out what you should know about heart rate and how it may help you achieve your fitness goals faster.

What does heart rate measure, anyway?

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Heart rate measures how fast your heart is beating.

In the simplest of definitions, heart rate, or pulse, is the number of times your heart beats in a minute (hence why it’s abbreviated as “BPM” for “beats per minute”). It measures how intensely your heart is pumping and can therefore be used as a proxy for how hard you’re working.

“Measuring your heart rate during exercise is a key tool to help you understand how intense your workout is,” says Tami Smith, an ACE-certified personal trainer. “By measuring your heart rate, you're able to gauge your exertion more accurately. For example, you might think that you’re working hard and to your max capacity, but your heart rate [might say] you’re still in a low zone and can push a little harder.”

What is resting heart rate?

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Resting heart rate is an indicator of cardiovascular health.

Your resting heart rate is the number of times your heart beats per minute when your body is most relaxed, either when sitting still or lying down. It’s typically between 60 BPM and 100 BPM, but it’s common for athletes or avid exercisers to see resting rates as low as 40 BPM. On average, men will have lower resting heart rates than women because their hearts are larger, which means they don’t have to work as quickly to pump the necessary amount of blood. A lower resting heart rate is a sign of good cardiovascular health because it means your heart doesn’t have to work as hard to pump blood throughout the body.

“The more conditioned the heart muscle actually is, the less it has to work at its resting state,” says Jessica Shepherd, MD and chief medical officer at Verywell Health. In turn, that means if you increase the aerobic exercise you do, the lower your resting heart rate can become (at least to the point where your heart reaches its best muscular shape possible).

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How can I use my heart rate during my workout?

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Heart rate can be a useful tool to use during workouts.

All aerobic activity does wonders for your cardiovascular health, and moderate- or vigorous-intensity exercise such as brisk walking, running, or rowing can maximize those benefits. Taking your pulse can help you figure out how intense your nightly jog, bike ride, or yoga class is, and can guide you to make adjustments to get to the intensity level you want.

Monitoring your heart rate can be especially useful during high-intensity interval training (HIIT) when you’re alternating between high-intensity and low-intensity segments. “I find the biggest benefits come with workouts where the goal is to raise your heart rate as much as possible within your working session and then allow it to come back down during your rest period,” Smith says. “A heart rate monitor will tell you exactly where you're at exertion-wise and will help you understand what makes your heart rate increase and decrease.”

Conversely, you can also check your pulse to make sure it doesn’t spike too high or too often, which is valuable in situations where a doctor wants you to keep your heart rate below a certain threshold and/or to monitor a medical condition.

So what should my heart rate be when exercising?

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Your pulse will vary during workouts.

To find your target heart rate, you need to know your maximum heart rate. Unlike resting heart rate, which is something that will change based on your cardio fitness, your max heart rate is determined by genetics and generally diminishes as you age. Therefore, the simplest way—albeit not the most accurate for all people—to calculate your max heart rate is to subtract your age from 220. For moderate-intensity aerobic exercise, your target heart rate will be up to 70% of that max, and for vigorous intensity, you’re looking for 70% to 85%. The American Heart Association (AHA) has a table you can reference to find your maximum and target zones based on your age.

That said, higher exertion isn't always better, and your target heart rate will change based on your goals. If you want to maximize the cardiovascular benefits of a HIIT workout, aim for a vigorous-intensity heart rate during your "on" segments, allowing your heart rate to drop significantly between bouts. “Not every workout is meant to be done at 100% of your ability,” Smith says. “There’s a lot to be said for controlling your heart rate during certain workouts like a tempo run where your goal is to keep an even keel throughout the whole workout.”

What are heart rate zones?

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Know your heart rate zones.

In some cases, workouts will call for you to reach or maintain your heart rate in a particular "zone." There are five heart rate zones, ranging from very light intensity to max intensity. The five heart rate zones are:

  • Zone 1: This is when your heart rate is at 50% to 60% of your maximum heart rate. You may find yourself in this zone while walking or cycling at a low intensity. This zone can be great for active recovery days, as well as a warm-up before or a cool-down after an intense workout.

  • Zone 2: Here, your target ranges from 60% to 70% of your maximum heart rate. This zone improves endurance and can work to build muscle and burn fat. Walking or cycling at a moderate pace will get you into this zone, but you should feel like you could stay at this intensity for a long time.

  • Zone 3: In zone 3, your heart rate will be 70% to 80% of your maximum. Exercising in this zone improves your aerobic fitness and builds heart-muscle strength. You’ll be sweating a little more and breathing heavier, like you could carry a brief conversation but couldn’t sing.

  • Zone 4: In the fourth zone, your heart rate will be 80% to 90% of your maximum heart rate. You’ll be sweating hard and your breathing will become more rapid. You shouldn’t be able to carry a conversation at this point. You’ll likely get in this zone while running, cycling, or rowing at a high intensity.

  • Zone 5: In the top zone, your heart rate will be 90% to 100% of your maximum. This means you’re working as hard as you possibly can, like a sprint at the end of your run or your “final push” on a rowing machine before hitting your time goal.

It’s important to exercise in various heart rate zones to get the most benefits and improve your overall fitness. These heart rate zones can be useful when evaluating your workout intensity, but ranges may vary from person to person. You may notice that the numbers you’re seeing don’t correspond with the effort you’re feeling. You may struggle to hit even the 70% lower end in a vigorous effort, or you may find the higher end feels too easy. This likely means that you will need to adjust your max heart rate up or down and recalculate your target zones accordingly. If it’s medically appropriate, the best way to reset your max heart rate is to warm up well then do a high-intensity effort for at least a few minutes and see what high numbers your monitor gives you.

What is the “fat-burning” zone?

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Exercising in the fat-burning zone may not be the best way to lose weight.

On large fitness equipment and some fitness trackers, you might notice something called the “fat-burning zone." The fat-burning zone often refers to zones 2 and 3, where you are working out at a lower to moderate intensity level. In this zone, your body is likely to burn proportionately more calories from fat than from carbohydrates, hence the name.

Does that mean that working out in this supposed fat-burning is the best way to go about losing weight? Not really. Losing weight is a matter of burning more total calories than you take in. At a higher heart rate, you’ll burn more calories overall (and possibly more fat), even if more of those calories come from carbs. If your goal is to lose weight, you’re better off working at a higher heart rate (or doing intervals of high effort and recovery) to burn more calories than you are focusing on burning fat specifically.

Can my heart rate be too high or too low?

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Stay safe while exercising, and know when you need to rest.

Getting your heart rate into the “right” range can take time, especially if you do little aerobic exercise to begin with. “A lot of people, when they first start working out, see their heart rate skyrocket because [their heart] is working hard,” Dr. Shepherd says. “What you’ll find in time when you continue to exercise and have some consistency, is that your resting heart rate [will lower] and your target heart rate will be in the [zones] it should be.” If the number you're seeing doesn't jive with the effort you're feeling, your best bet is to listen to your body and simply learn from the numbers as you settle into your new routine.

Once you find your base, if you still see that your exertion pulse is higher than you think it should be, you could be expending more energy than you should for that workout, or you may need to recalibrate your maximum heart rate to a lower value (and thus, your heart rate zones). “If you’re overexerting yourself for prolonged periods, keeping your heart rate up in your upper zones, there is such a thing as getting your heart rate too high,” Smith says. “The highest zones are meant to be hit in short bursts, not for prolonged periods, as that can lead to health issues like fatigue, burnout, and cardiovascular issues.”

On the other hand, a too-low workout pulse likely just means you’re not pushing yourself as hard as you could to see maximum benefits, and though it could signal an underlying medical condition, Smith says this is unlikely. Still, especially when first starting out, the AHA recommends aiming for the lowest target heart rate and working your way up. This can help you avoid fatigue, burnout, or injury.

How can I measure my heart rate?

A woman strapping on a chest heart rate monitor.
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For the most accurate reading, go with a chest strap.

You don’t necessarily need any equipment to measure your heart rate. You can find it manually by placing two fingers on your radial artery (inside of your wrist, below the thumb) or carotid artery (on the side of your neck) and press gently until you feel your pulse. Once you find it, set a timer for one minute and count how many beats you feel.

That said, this manual method can be inconvenient mid-workout. It’s much easier to just look at a screen and read the number. Due to the distance between your heart and your wrist, fitness trackers and smartwatches aren’t quite as accurate as a heart rate monitor worn on the chest. They’re still great options for those who want to keep an eye on their heart rate trends, but won’t give precise measurements exactly as they are changing in real-time, and shouldn't be relied upon for interval workouts.

If you want a more accurate reading, your best shot is a chest strap. Two well-reviewed options are the Polar H10 and the Garmin HRM-Pro. The Polar H10 uses electrocardiogram (ECG) technology to accurately detect your heart rate and can be paired with exercise equipment such as Peloton bikes so you can easily keep track of your intensity throughout your workout. Reviewers love how easy it is to sync the Polar H10 and how comfortable the strap is to wear throughout different workouts.

The Garmin HRM-Pro is a great option for runners because it measures heart rate and running metrics like stride length and ground contact time to help you improve your form. Reviewers say this monitor is accurate and easy to use, and all the data it gives makes it well worth purchasing.

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