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Newest Smartwatches Move From Tracking Fitness to Monitoring Health

Added features can keep you heart-healthy — and may detect signs of COVID-19

Sleep tracking functions on Fitbit Sense health tracking smart watch wearable device, San Ramon, California, September 22, 2020. (Photo by Smith Collection/Gado/Getty Images)

Smith Collection/Gado/Getty Images

Sleep tracking functions on a Fitbit Sense smartwatch device

En español | The pandemic may have kept you a bit more stationary than you would have preferred these past six months. But because COVID-19 and this year’s strain of flu are in the air right now, you may be more eager than ever to track your fitness activity and get a better handle on what’s happening inside your body.

Insights into your health may come straight from your wrist. Apple’s latest Series 6 smartwatch that starts at $399, coupled with the watchOS 7 software upgrade that some older models can take advantage of, can help you measure your cardio fitness and blood-oxygen consumption while also detecting irregular heartbeats, excessive exposure to loud noises and how much sleep you’re getting.

The watches even can remind you to wash your hands periodically with a 20-second countdown timer that may automatically kick in to ensure you’re washing long enough. And recent Apple Watches can summon emergency medical assistance should you fall and become immobilized.


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Rival wearables from Fitbit, Samsung and other companies also are providing digital biomarkers that provide visibility into your health — well beyond the steps counted and calories burned that have long defined such devices.

“This is a new era where we have an opportunity to reach the patients outside the walls of the hospital,” says Nino Isakadze, M.D., a cardiologist at Johns Hopkins Hospital in Baltimore who studied atrial fibrillation (A-fib) and wristband technology during her residency. “Patients can be empowered by having this type of data and be able to track their progress and be more aware of their health overall.”

Smartwatches share data with companion health apps on your iPhone or Android devices. And worth noting for those enrolled in Medicare is that some smartwatches are available at a discount as a member benefit to participants of some Medicare Advantage plans.

4 features on some smartwatches

1. Electrocardiogram. In 2018, Apple took a major step in putting power in the hands of consumers when it added an electrocardiogram app to its Series 4 Apple Watch models — which has carried over to the Series 5 and Series 6. The app, which is called ECG rather than the more commonly known EKG abbreviation, can detect A-fib, an irregular heartbeat that is a major risk factor for stroke.

Fitbit recently received regulatory clearance from the U.S. Food and Drug Administration for its own EKG app, coming to the Fitbit Sense health-oriented watch in October. And Samsung has added its own FDA-cleared heart-monitoring ECG app to the Galaxy Watch3, starting at $370, and Galaxy Watch Active2, starting at $270.

“Patients can be empowered by having this type of data and be able to track their progress and be more aware of their health overall.”

— Nino Isakadze, M.D., Johns Hopkins Hospital

EKGs in general measure the timing and strength of the electrical pulses that keep your heart pumping. On the Apple Watch, the ECG kicks into action when you launch the app and hold your finger against the digital crown, the home button on the upper right side of the watch, for 30 seconds. Electrodes are built into the back crystal and digital crown of the watch.

If you receive a “sinus rhythm” result, it means the watch detected a normal heartbeat, not A-fib. Regardless of the result, you’re urged to seek medical attention if you experience any symptoms. Apple makes it clear that its watch does not check for signs of a heart attack.

2. Measuring the skin. Fitbit added an electrodermal (EDA) sensor to its Fitbit Sense watch ($330). When you place your palm over the face of the device, sensors can detect subtle electrical changes in the sweat level of your skin. Factored with your heart rate, sleep and activity data, Fitbit calculates a stress management score between 1 and 100, with a higher number translating to fewer physical signs of stress and a lower number meaning more signs.

Fitbit may recommend breathing exercises and other mindfulness tools to help you manage stress. But after a free trial period, you’ll have to sign up for a premium subscription service for a deeper dive into the metrics.

Another dedicated sensor on the Sense can detect variations in skin temperature. This feature is not yet available on Apple or Samsung smartwatches.

Apple Watch Series 6 - Displaying blood oxygen measurements

Apple, Inc.

Apple Watch Series 6 displaying a blood oxygen reading.

3. Sleep tracking. Some devices, including high-end Fitbits and Galaxy smartwatches, track the quality of your slumber time right down to various sleep stages and the number of times you wake up in the middle of the night. Apple’s watch is more about setting up the conditions so that you get a good night’s sleep, starting with a wind-down routine before bedtime.

Of course, if you’re planning to sleep with any of the smartwatches, make sure they are charged before you go to bed, and if needed, give them some extra juice when you wake up. Only the Fitbit Sense had longer than a 24-hour day’s battery life, in what PC Magazine considered normal use.

4. Blood oxygen. Fitbit, Garmin, Mobvoi, Samsung and now Apple’s Series 6 can all measure blood-oxygen levels. Series 6 obtains a measurement from a quartet of clusters of green, red and infrared LEDs on its rear and four photodiodes spaced and isolated between them to determine the color of your blood.

Measurements are automatically collected throughout the day or when you’re asleep. You also can launch an app to take a manual reading by steadying your wrist on a table, with the watch display facing upward, tapping on Start, and then waiting patiently while a timer counts down for 15 seconds.

While most healthy adults report levels between 95 percent and 100 percent, what does a lower blood-oxygen reading signify? Blood oxygen is an indicator of early signs of circulatory, heart or lung function issues, such as anemia, neurological problems or sleep disorders, says Leslie Saxon, M.D., a professor of medicine and executive director at the Center for Body Computing at the University of Southern California.

Keep results in perspective

Don’t freak out if any result is out of kilter, but see how it compares with your baseline. Yet don’t ignore warning signs either.

“The most important thing is how one is feeling and the symptoms,” Isakadze says. “If someone is not feeling well, I would say no matter what the numbers show on the oxygen levels or the ECG, it would still be very important to seek care.”

These are still early days for what smartwatches can track. Neither the Apple Watch nor Fitbit can monitor blood-glucose levels or high blood pressure without the use of other devices right now, which would provide a huge benefit to patients with diabetes or hypertension.

But specialized wearables are available in this area. A start-up called Movano is developing a noninvasive needle-free glucose watch, for example. Meanwhile, data culled from the wrist is becoming fertile ground for researchers. 

Apple recently announced a study with Anthem and the University of California, Irvine, to examine how its watch might help individuals manage asthma. Another Apple study with the Ted Rogers Centre for Heart Research at the Peter Munk Cardiac Centre in Toronto, is set to investigate how the watch might help lead to better outcomes for patients with heart failure.

Apple researchers also are teaming up with University of Washington Medicine in Seattle on a study to learn if physiological measurements around heart rate or blood oxygen can be used to detect signs of acute respiratory infections, such as influenza and COVID-19.

While the results of such studies will take time, you can learn a lot by looking at your wrist right now.

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