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#AskPCMag: How Accurate Is the Apple Watch's Heart Rate Monitor?

Does the Apple Watch have an accurate heart rate monitor? Which smartwatch has the best sleep tracker? Can you use a heart rate monitor while swimming? We have answers to these fitness tech questions and more.

By Angela Moscaritolo
May 5, 2020

At PCMag, we strive to help you make the most informed decisions when purchasing technology. If you have questions, our team of experts is here to help.

We recently asked you to submit questions about fitness technology on Twitter. I sat down with PCMag's editor-in-chief Dan Costa for a virtual chat to answer your best fitness tech questions.

Check out the full interview below. And remember, if you have any tech questions, send it our way on Twitter using the hashtag #AskPCMag. You might just see it answered in an upcoming video.

Ask PCMag: How does the Apple Watch compare to other fitness trackers?
PCMag Logo Ask PCMag: How does the Apple Watch compare to other fitness trackers?

Which smartwatch has the best sleep tracker? - Austin

There are plenty of fitness tracker/smartwatch hybrids that can track your sleep very well. 

One of my favorites is the $149.99 Fitbit Charge 4, which was released last month. On top of tracking your light, deep, and REM sleep, it graphs out your sleeping heart rate and your estimated oxygen variation, or the changes in your blood oxygen saturation. It can tell you if your estimated oxygen variation is high, which can indicate breathing issues. It also gives you a sleep score from one to 100, taking into account your sleep quality and duration.

The Fitbit Charge 4 tracks your light, deep, and REM sleep, plus your sleeping heart rate

Another device that does sleep tracking really well is the Garmin Vivoactive 4, which normally costs $349.99 but is currently on sale for $269.99. It has a Pulse Ox sensor, which gauges oxygen saturation in the blood. It reports on your respiration, or average, highest, and lowest number of breaths per minute while sleeping. 

Finally, another of my recent favorites for sleep tracking is the Polar Grit X, an outdoor multi-sport GPS watch. It’s pricey at $429.99, but it gives you a Nightly Recharge sleep recovery measurement showing how your body was able to recover from training and stress, based on information it collects about your sleep and autonomic nervous system. Then, depending on how well your body was able to recover, it gives you training advice like “go for it” or “take it easy.” 

How accurate is the latest Apple Watch compared with other fitness trackers? If you focused just on fitness and health, is it still the best even then, or are other dedicated devices better? - Jamie

In our testing, the Apple Watch Series 5 delivered excellent health and fitness accuracy. We tested it against a Polar H10 chest strap, a Stryd footpod, and the Fitbit Versa 2, and its heart rate readings and step counts were spot-on, so it can definitely replace a dedicated fitness tracker. That said, if you’re just interested in fitness tracking, there are many other excellent and more affordable options like the Fitbit Charge 4 and the Garmin Vivoactive 4.

The Apple Watch Series 5 offers accurate heart rate readings, but doesn't track your sleep out of the box

Also, sleep is a big element of overall health, and the Apple Watch lacks in that department. Out of the box, the Apple Watch doesn’t offer sleep tracking. And while you can get third-party apps that turn it into a sleep tracker, the Series 4 and Series 5 models only have about 18 hours of battery life, so you’ll probably want to take it off at night to charge. 

Are any heart rate monitors waterproof, and OK to use while swimming? - Keith

Yes. There are lots of waterproof heart rate monitors, including the Polar H9, our most recent Editors' Choice. It uses an ECG (electric pulse) for taking your heart rate, rather than the less accurate optical method. Other good options include the Polar H10 and the Scosche Rhythm24

Wrist-worn wearables like the Polar Grit X offer 24/7 heart rate monitoring

Aside from these, some wrist-worn fitness trackers, including the Garmin Vivoactive 4 and the Polar Grit X, can monitor your heart rate optically while swimming. They also eliminate the need for wearing a chest strap heart rate monitor, though you might prefer one for accuracy. 

I recently had a double bypass and they implanted a pacemaker as a result of which none of the chest straps (Garmin) work anymore. After consulting with both Saint Jude, the manufacturer, and Garmin, I was told there was indeed an incompatibility. Since wrist measuring is not as exact as the chest strap, could you tell me if there is a solution?  - Jacques

I reached out to Garmin and Polar about whether their heart rate monitors cause interactions with pacemakers. In terms of safety, Garmin said its heart rate monitors are essentially passive devices, so they are safe. They don't transmit any electricity into your body, they merely measure electrical signals of your body. 

A Garmin spokesperson said, “It is possible that there are some pacemakers out there whose signals confuse our HRMs, in which case definitely the customer can use wrist HR measurement as an alternative, if it meets his/her needs for accuracy and reliability.”

Similarly, a representative from Polar said, "People with a pacemaker should be fine to use the company’s wrist-based and chest heart rate monitors, however it is up to the individual to decide and Polar can not 100 percent say that it will not interfere.” 

As for the accuracy of optical heart rate monitors in wrist-worn wearables, you are correct that chest straps are more accurate, but they’re not something you want to wear all day. Wrist-worn wearables are more convenient, comfortable, and give you a picture of your heart rate 24/7.

The Garmin Vivoactive 4 is water resistant to 164 feet and optically tracks your heart rate while swimming

On this topic, Polar says, “Based on our own validation studies, our optical heart rate readings are very similar to ECG-based readings in many of the most popular sports, mainly running and cycling. That said, it’s still true that if you want the universally most accurate heart rate tracking solution, reach for the chest strap.”

What are the best online yoga or fitness classes? - Kirsten

Since COVID-19 changed the way we live, many yoga studios have shifted to online classes via Facebook Live or Zoom, and are offering them for free or by donation. As social distancing continues and businesses remain closed, I suggest checking with your local yoga studio to see if they are offering classes online right now. You might find that your favorite local teacher is still teaching classes that you can take from home. 

I also recommend Yoga With Adriene on YouTube. All of her classes are free, well produced, and she is a wonderful teacher. She has lots of different styles of classes—everything from challenging arm balance flows to relaxing, restorative sessions—so you’re sure to find one that works for you. 

Another resource worth mentioning is the yoga and fitness app Grokker, which is currently free through May 31. 

The Echelon Reflect workout mirror isn't cheap, but it looks good and offers a range of fitness classes

And if you have a healthy chunk of money to spend, the Echelon Reflect workout mirror, which starts at $1,039.98, offers a range of yoga classes, plus everything from boxing and Pilates to conditioning, strength, and Zumba.

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About Angela Moscaritolo

Managing Editor, Consumer Electronics

I'm PCMag's managing editor for consumer electronics, overseeing an experienced team of analysts covering smart home, home entertainment, wearables, fitness and health tech, and various other product categories. I have been with PCMag for more than 10 years, and in that time have written more than 6,000 articles and reviews for the site. I previously served as an analyst focused on smart home and wearable devices, and before that I was a reporter covering consumer tech news. I'm also a yoga instructor, and have been actively teaching group and private classes for nearly a decade. 

Prior to joining PCMag, I was a reporter for SC Magazine, focusing on hackers and computer security. I earned a BS in journalism from West Virginia University, and started my career writing for newspapers in New Jersey, Pennsylvania, and West Virginia.

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