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If you have a fitness tracker or smartwatch, you might have noticed that your device provides you with a regular report on your heart rate. Or perhaps you regularly use a treadmill or an elliptical equipped with a chest strap or a built-in heart rate monitor and you’ve wondered whether you should use one of those devices.
Heart rate is one of the best tools we have to gauge how hard you are working, says Phil Clifford, associate dean for research in the College of Applied Health Sciences at the University of Illinois at Chicago. Heart rate can help you assess whether you’re meeting your own personal goals or federal fitness guidelines, which say most Americans should aim for a minimum of 150 minutes of moderate-intensity exercise or 75 minutes of vigorous-intensity exercise each week.
Hitting those guidelines will improve your overall health and heart health, lower your risk for chronic diseases such as diabetes and for various forms of cancer, improve your cognitive function, boost your mood, improve sleep and more.
Measuring heart rate can help you learn whether your workout is moderate, vigorous or not quite either — so you can adjust accordingly.
Heart rate measures how many times per minute your heart beats. When resting, a person’s heart usually beats 60 to 100 times per minute, according to the American Heart Association. In general, fitter people have lower resting heart rates — trained athletes’ hearts might drop to as low as 40 beats per minute (bpm) because they are functioning more efficiently.
As your muscles start pumping when pushing through an aerobic activity, such as running, biking or swimming, they need more oxygen. That’s why you breathe harder and your heart starts pounding. Each beat pumps oxygen-filled blood through your body, which is why tracking your heart rate can tell you how hard you’re working.
“Heart rate is a stand-in for what scientifically is measured as the volume of oxygen you’re consuming,” says Peter Anzalone, senior test project leader for fitness equipment at Consumer Reports.
If you are going all out, the measurement of how much oxygen you’re capable of consuming is known as your VO2 max, which researchers consider the best measure of fitness capacity, Clifford says.
If you are sedentary and just beginning to exercise, you don’t need to track heart rate, Clifford says. Instead, start by just trying to move more. “There’s a health risk to just sitting, and it can be counteracted by just getting up and moving,” Clifford says.
Once you’re comfortable with some exercise, you can start striving toward hitting fitness targets for moderate intensity exercise. In that case, measuring your heart rate could help you understand how those workouts should feel.
More serious athletes, like anyone training for a 10k or half-marathon, will get even more benefit from tracking heart rate regularly because subjective measures like your perceived exertion can vary daily.
You can also estimate levels of exertion without tracking your heart, says Cris Slentz, an assistant professor in the departments of medicine and cardiology at the Duke Molecular Physiology Institute in Durham, N.C. During moderate exercise, your breath should speed up a bit, and you’ll begin to sweat after about 10 minutes, according to the Mayo Clinic. You should be able to talk, although not sing. During vigorous exercise, it’s hard to say more than a few words.
If you are going to track your heart rate, you’ll need to use a monitor.
Chest strap monitors are probably best in most cases, Anzalone says. These are worn around your chest, directly against your skin, and detect your heart rate electronically.
Monitors worn around the wrist that detect heart rate with an optical signal, including fitness trackers like Fitbits and smartwatches like the Apple Watch, can also be very accurate.
Monitors built into machines such as treadmills and ellipticals can work, but are not always as accurate, Anzalone says.
You can use your heart rate to measure and change your exercise intensity, which will help you plan and understand your workouts better. There’s not a particular heart rate that corresponds to a particular intensity; instead, it’s different for each person.
To figure out which levels of exertion count as moderate or vigorous exercise for you, calculate what’s known as your heart rate reserve, according to the American College of Sports Medicine’s Guidelines for Exercise Testing and Prescription.
There are a few steps involved, so get your calculator or pencil ready.
● Calculate your maximum heart rate. Subtract your age from 220 for your estimated maximum heart rate. The number you get may vary by up to 20 bpm from your actual maximum heart rate, but this is a standard way to estimate without doing a stress test. You may have a more exact number if you’ve done a maximum exercise stress test or if you are an athlete who has measured your heart rate after an all-out level of exertion.
● Measure your resting heart rate. You can do this with your fitness tracker or by using a timer and counting how many times your heart beats in a minute. You can also count how many times it beats in 15 seconds and multiply that by four.
● Calculate your heart rate reserve. Subtract your resting heart rate from your max heart rate.
● Find your ranges for moderate and vigorous exertion. Your heart rate range for moderate intensity activity is 40 to 59 percent of your heart rate reserve added to your resting heart rate. Your heart rate range for vigorous intensity activity is 60 to just under 90 percent of your heart rate reserve added to your resting heart rate.
Going above that vigorous level can be dangerous if you have underlying heart problems or multiple risk factors for cardiovascular disease, says Slentz, though it’s something that some people do during interval training or other all-out exercise. And if you have known risk factors or heart problems, you should also avoid exercise in the “vigorous” range unless you’ve consulted your physician.
For anyone, activity at levels of exertion reaching 90 percent of max heart rate or above is extremely difficult to sustain.
Once you have a sense of how vigorously you are exercising, you can map out your workouts to ensure that you are hitting the minimum exercise guidelines suggested by the government — or, better yet, surpassing them.
You can also push yourself to specific targets, give yourself goals based on actual (rather than perceived) exertion and use your heart rate to help plan interval workouts.
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