It used to be that only professional athletes used target heart rate training—a technique that helps you figure out the best workout intensity for your fitness goals. And for good reason: It required wearing an uncomfortable chest strap and hiring a coach who could make sense of all the data!
But those days are gone. Now, cutting-edge activity trackers, like Fitbit Alta HR, Fitbit Charge 2 and Fitbit Blaze—can measure heart rate via a wristband instead of a chest strap. They even sync with a free app that does all the necessary calculations for you—because let’s be honest, who wants to do math when you’ve got a workout to do? Instead, this is a ridiculously easy way to optimize every sweat session.
Here’s how target heart training works and how you can use it—even if you don’t have an activity tracker.
How to Set Your Heart Rate Zones
Step one is to figure out your max heart rate or the highest number of times your heart can safely beat in one minute.
“Max heart rate doesn’t have anything to do with performance or how fit you are,” says Roy Benson, running coach and co-author of Heart Rate Training. It’s simply a function of genetic factors, such as the size of your heart. Some hearts are larger and need to beat fewer times, while smaller hearts beat more often to push blood around your body.
There are a few different ways to find out your max heart rate. The most effective method involves getting a maximal stress test at a cardiologist’s office, health lab or sports science facility, says Benson. The technician will put you on a treadmill and gradually increase the pace and incline until you have to stop.
If you don’t have the extra time or money to spare on a stress test, you can estimate your max heart rate using the industry-standard formula of 220 minus your age. So a 30-year-old would have a max heart rate of 190 (220-30=190).
Once you know your max heart rate, you can calculate your heart rate training zones. Each one represents an intensity level—or percentage of your max heart rate—that taps into a different energy system in the body, producing specific results. Here’s a breakdown, including each zone’s corresponding rate of perceived exertion (RPE)—i.e. how hard you feel like you’re working on a scale of 6 to 20:
Intensity: Vigorous (85 to 100 percent of your max heart rate)
Feels like: You can only sustain this effort for a few minutes and uttering more than one word at a time is difficult.
Benefit: Increases performance speed
Intensity: Hard (70 to 84 percent of your max hr)
Feels like: You’re breathing harder and only able to speak in short sentences, but the pace is sustainable—you’re not fantasizing about quitting or worried that you won’t be able finish the workout.
Benefit: Builds cardiovascular fitness and muscle strength
Intensity: Moderate (50 to 69 percent of your max hr)
Feels like: Your heart rate and breathing is elevated, but you’re still able to talk in full sentences or sing out loud.
Benefit: Builds aerobic endurance and teaches the body to burn fat as fuel
Get in the Zone
Now that your heart rate zones are set and you know what they mean, you can work out at the right intensity for your fitness goals.
For instance, want to do some fat-burning aerobic endurance exercise? Periodically check in with yourself during your workout to make sure your heart rate is between 50 to 69 percent of your max. If you’re using a Fitbit tracker with PurePulse or another heart rate monitor, your device should be able to tell you which heart rate zone you’re in.
If you’re not using a device, do a quick body check and compare how you feel and what you’re experiencing to the guidelines above. Over time, knowing which zone you’re in will become more intuitive.
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