Should I use a smartwatch to track my health data? A doctor explains | CNN

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I ride a recumbent bike while wearing my smartwatch, hoping that tracking my fitness and health metrics will inspire me to exercise more.

Smartwatches aren’t just for texting, listening to music, and telling the time (that’s a bit old-fashioned) anymore: they’re now an integral part of some people’s health habits. Can they detect heart problems, like irregular heartbeats or even heart attacks? What about their usefulness for measuring oxygen levels or blood sugar? And can they help you sleep?

According to Insider Intelligence/eMarketer, more than a quarter of the U.S. population wore a smartwatch or other connected device used to monitor their health and fitness in 2023. By 2026, the company predicts that more than 100 million Americans will use a smart wearable device.

To answer my smartwatch-related health and fitness questions, I spoke with CNN wellness expert Dr. Leana Wen. Wen is an emergency room physician and associate clinical professor at George Washington University. She owns a smartwatch and loves to exercise. She was previously Baltimore’s health commissioner.

CNN: Let’s start with the basics. How do you define a smartwatch and how can people use it to track their physical activities and fitness?

Dr. Follow Wen: A smartwatch is a type of wearable technology device that looks similar to a wristwatch. Most are Bluetooth enabled and can connect the watch to a smartphone. This allows the user to access certain features of the phone, such as receiving text messages, listening to music, or even answering phone calls and emails.

Many smartwatches also track fitness and health data. One feature I really like is step tracking. Studies have shown that setting daily step goals can reduce the risk of heart disease and premature death.

A study published in March showed that for people who were sedentary most of the day, taking between 9,000 and 10,000 steps a day reduced the risk of developing cardiovascular disease by 21% and the risk of premature death by 39%. Another study, published last year, showed that even 4,000 steps a day was enough to reduce the risk of premature death.

Wearing a smartwatch can track the number of steps taken throughout the day. This can remind people of their goals and be a way to motivate them to take more steps.

CNN: You’re a runner and triathlete. How do you and other active people use your smartwatches to help with your training?

Magnifying glass: Many active people monitor their heart rate during exercise to keep it within a certain range. Many endurance athletes like runners, cyclists, and triathletes spend the majority of their time training in what’s called zone two, or the endurance zone. This is where your heart rate is below 70 to 75 percent of your maximum heart rate. It feels like you’re working, but not so hard that you can’t keep up the exercise.

A smartwatch with a heart rate monitor can help athletes monitor their heart rate to stay in their target zones. More advanced smartwatches have more fitness features, such as tracking pace, distance, and cadence, and some can even detect the type of sport they’re doing for those switching between disciplines. Some have GPS data and can provide directions to the wearer.

CNN: I’ve seen smartwatches that claim to be able to detect heart problems. Can they really be used to signal heart attacks?

Magnifying glass: Smartwatches are not approved to diagnose heart attacks. If you are experiencing chest pain and your smartwatch indicates that your heart rate and EKG are normal, this does not mean that you are okay. You should seek immediate medical attention.

It’s important to keep in mind that smartwatches are not a replacement for medical-grade monitoring equipment. People who are told by their doctor that they need a specific heart monitoring device should heed this advice.

CNN: What about irregular heart rhythms?

Magnifying glass: There are many smartwatches that claim to detect an irregular heartbeat called atrial fibrillation. This heart rhythm can increase the risk of stroke if left untreated and it is important to diagnose it.

The Apple Watch, Fitbit Sense and Samsung Galaxy are among a handful of smartwatches that have received approval from the U.S. Food and Drug Administration for their ability to detect irregular heart rhythms in a subset of adults without a history of atrial fibrillation.

If a person who did not previously have heart abnormalities receives such a notification, they should contact their primary care physician and ask about next steps, which may include an in-office ECG and ongoing medical-grade monitoring.

I want to emphasize once again that you should also listen to your body. If you experience heart palpitations, shortness of breath, chest pain, dizziness, or other strange sensations, you should contact your doctor, even if your smartwatch indicates that your heart rate and rhythm are normal.

CNN: What about using smartwatches to measure oxygen levels or blood sugar?

Magnifying glass: The accuracy of smartwatches for measuring oxygen levels varies. In my opinion, if you need to measure oxygen levels because of underlying lung problems, for example, you should use dedicated equipment for this purpose. A pulse oximeter is inexpensive and easily portable. They are generally accurate, although recent studies suggest they are less so in people with dark skin.

When it comes to blood sugar, the FDA issued a stern warning this year advising consumers not to “purchase or use smartwatches or rings that claim to measure blood sugar.” These devices can give inaccurate blood sugar readings.

People with diabetes who need precise measurements to dose their medications may end up giving themselves too much or too little medication if their blood sugar readings are inaccurate. This can be dangerous. They should continue to use the measuring devices prescribed by their doctor, knowing that smartwatches are not yet able to replicate the accuracy of this medical-grade equipment.

CNN: Can using smartwatches help you sleep?

Magnifying glass: It’s possible. Many smartwatches monitor your sleep and can tell you how long you slept and how much time you spent in each sleep stage.

Personally, I find this information useful. I have always had trouble sleeping, so I am constantly experimenting with different things, such as meditating before bed, reading a book, and sleeping in different positions. I like the data my smartwatch gives me on sleep quality and duration. I can try to correlate this with changes I make to my sleep environment to see which changes work and which don’t.

I also like the feature on my smartwatch that tracks heart rate variations during sleep. This is a measure of the variation in time between each heartbeat. Everyone’s baseline heart rate variation is different. By knowing your own baseline, you can track changes over time.

I’ve noticed, for example, that when I’m not sleeping well or have recently had intense workouts, my heart rate variation decreases, indicating increased stress and less recovery. I can then work on prioritizing extra sleep or adjusting my training based on this data.

My biggest takeaway from smartwatches is that they are useful for people who love data. I am one of them, and I love my smartwatch because it provides me with data that can inform and motivate me. There are also people who may find all this data useless or even stressful. The key is to do what works for you. Smartwatches are a tool that can help you achieve your health and fitness goals; they should not add more pressure and stress to your life.

CNN: I’ve heard that smartwatches aren’t always suitable for people who exercise compulsively.

Magnifying glass: Some people might benefit from a break from data tracking. Exercise should be fun and enjoyable, and if all the data adds pressure and stress, it’s worth leaving the smartwatch at home a few times to see if it makes the activity more enjoyable. Plus, it’s always important to listen to your body.