Modern smartwatches have a wide array of heart-rate monitoring features. That includes passive all-day monitoring as well as spot checks for specific metrics. Some will even alert you if your heart rate suddenly spikes when it shouldn’t. The most advanced devices also have FDA-cleared electrocardiograms that may help detect atrial fibrillation. Show These are impressive features considering that, just a decade ago, smartwatches were basically pedometers. In practice, heart rate monitoring can be a helpful tool for people hoping to understand more about their bodies or measure their fitness progress over time. For instance, some athletes prefer to train in heart rate zones — which is hard to do unless you can check it in real time. There have also been several stories of people who say their smartwatches saved their lives thanks to abnormal heart rate alerts. That said, it’s important to remember that these aren’t medical devices. At the end of the day, they’re not capable of diagnosing you with any sort of condition. And, even if they were, doctors are still on the fence about how to handle wearable data that consumers collect on their own. There are nuances to how these features work and plenty of reasons why you might get inaccurate readings.First, we’ll cover how heart rate monitoring works and how to measure your heart rate. Then we’ll get into what EKG-capable smartwatches can and cannot do and how to use the EKG feature with the current crop of smartwatches. The sensor array on the back of the Series 6 is capable of both EKGs and PPG heart rate monitoring. Vjeran Pavic / The Verge How optical heart rate sensors workThe vast majority of wearables use a photoplethysmography (PPG) sensor — the green LEDs you see when you flip the device over. The LEDs shine light into your skin; the light that’s refracted back is translated by an algorithm into heart rate data. That includes your resting heart rate but also other metrics like VO2 Max and heart rate variability. While optical heart rate sensors have gotten better over the years, wrist-based PPG sensors still aren’t always accurate. A recent study found that these sensors didn’t work as well on darker skin or people with obesity. The wrist is also not the best place for a PPG sensor. There’s a lot of noise from your arm movements, and a company’s algorithm has to be able to effectively filter that out. That’s why you could wear the same smartwatch on each arm and still get slightly different readings. Fit is also an important factor. It varies from smartwatch to smartwatch, but here are a few general tips for getting the most accurate data possible.
Many smartwatches, including the Fitbit Versa 3, will allow you to view heart rate from your watchface Photo by Victoria Song / The Verge Viewing heart rate and settingsOnce you’ve paired your smartwatch, you should dive into the settings in your watch’s companion app. That’s where you’ll get to customize how often your watch measures your heart rate. Some watchesmeasure heart rate continuously by default; others will measure periodically to help extend battery life. For example, the Apple Watch measures your heart rate periodically when you’re still and while walking. It only measures continuously when you’re in a workout and for the three minutes after during recovery. You don’t have the option to change that. However, other devices like Garmin and Samsung watches may let you have more of a say. Each smartwatch maker designs their app differently, but you can usually find heart rate settings in your device’s settings or a health settings menu. Your watch may also be capable of low and high heart rate alerts. This means you’ll get a notification if, while at rest, your heart rate goes below or above a certain threshold. So if you’re sitting still and your heart rate spikes to 120 beats per minute, you might get a notification. Many watches will let you customize the range for these alerts. Below, we’ve outlined how to access these settings for some of the most popular devices and how to measure your heart rate. Apple WatchAccessing heart rate settings in the Watch app is easy Screenshot: Victoria Song / The Verge To access heart rate settings, open the Watch app and scroll down the list of installed apps to Heart. From here, you can enable a variety of health measurements:
Again, none of these are diagnostic features. To measure heart rate:
Fitbit trackers and smartwatchesTo access heart rate settings:
Here’s another method:
To view heart rate:
Samsung Galaxy WatchesTo access heart rate settings on the Galaxy Watch 4 and Watch 4 Classic:
Measuring heart rate on the Samsung Galaxy Watch Active Photo by Chris Welch / The Verge On Samsung’s Tizen watches:
To set up high / low heart rate alerts:
To manually measure heart rate:
The Withings ScanWatch’s EKG feature was recently cleared by the FDA Photo by Amelia Holowaty Krales / The Verge About EKGsThere are only a handful of smartwatches that have been cleared by the FDA to measure EKGs in the US. So even if the smartwatch you buy supports this feature, you’ll have to check whether it’s been granted regulatory clearance in your country. Assuming it has, EKGs on smartwatches work by reading electrical signals from your heart. The smartwatch’s heart rate monitor acts as an electrode, and by touching your finger to the case / digital crown, you create a closed circuit. After a short period of time, you’ll be told whether your heart rhythm for that particular reading — and only that reading — shows a normal rhythm or signs of atrial fibrillation. It bears repeating: no watch can give you an actual medical diagnosis. The most that you can do with this information is export it to a PDF that you can then share with your doctor. If you’ve got a clean bill of health from your doctor, you may not need to use this feature at all, and that’s perfectly fine! You should also be aware that you may get a few inconclusive readings. There are several reasons why that can happen. First, you generally have to remain very still to take these EKG readings — if you’re fidgety, that could result in an inconclusive result. Likewise, your skin might be a little wet, and that can screw up a reading. Each smartwatch maker will have its own suggestions for how to troubleshoot, but the gist is to relax and keep still while using the EKG feature. Apple WatchYou can only take EKGs on the Apple Watch Series 4, 5, 6, and 7. EKG results in the Health app Screenshot: Victoria Song / The Verge How to get started:
To export your results:
Samsung Galaxy WatchOnly the Samsung Galaxy Watch Active 2, Galaxy Watch 3, and Galaxy Watch 4 support EKG readings. How to get started:
To export your results:
Fitbit Sense and Charge 5Only the Fitbit Sense and Charge 5 can take ECG readings at this time. You can export your EKG results to a PDF and send it to your doctor Screenshot: Victoria Song / The Verge The ECG app should already be on your watch or tracker, but if not, here’s how to install (or uninstall) the app:
How to get started:
To export your results:
Withings ScanWatchWhile Withings has multiple EKG-capable watches, only the ScanWatch is cleared for use in the US. How to get started:
To export your results:
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