Reviewed by Brunilda Nazario, MD on May 28, 2021
Most mornings, before she makes breakfast, Brandi Andrade slips on a belt-like device called OsteoBoost, which has an oval box a bit bigger than a cellphone that rests on her lower back. With the flick of a switch, the box vibrates, which is intended to stimulate her bones to grow and strengthen by mimicking the effects of high-impact exercise such as jogging or brisk walking.
Andrade, 50, lives in Asheville, NC, and has osteoporosis, which weakens bones. She was one of the first people to test OsteoBoost, whose manufacturer is seeking approval from the FDA to sell the bone builder in the United States. If it’s approved, OsteoBoost will join the booming market for wearable health devices.
Medical tools that are worn on the body or attached to your clothes have been around for years, but thanks to advances in digital technology, some doctors and scientists believe that wearable devices are poised to have a major impact on health care. And if you count your steps or calories by glancing at your wristwatch, you have already joined the revolution.
Old Idea, Made New
The idea of wearing a device on your body to manage or monitor a health condition isn’t new. Eyeglasses, for instance, date back to the 13th century. More recently, the mid-20th century saw the arrival of the Holter monitor, a portable electrocardiogram device that detects irregular heartbeat, which patients wear for a day outside the doctor’s office. Wearable glucose monitors have made it easier for people with diabetes to keep tabs on their blood sugar since 1999. And the FDA approved the first “artificial pancreas” system, which automatically adjusts insulin levels for people with diabetes and is worn outside the body, in 2016.
However, advances in technology are making the miniature computers that run wearable health devices increasingly sophisticated, as well as even smaller. That means they can fit into more discreet places, such as a smartwatch or wristband. About 1 in 5 Americans wears a smartwatch or wearable fitness tracker, according to the Pew Research Center. Granted, some people who buy smartwatches never use them for more than checking the time and maybe their email. Yet many models of these wrist-worn devices come equipped to do much more, such as count your daily steps, monitor your heart rate, and track how many calories you burn and hours you sleep.
There’s growing evidence that using wearable health devices may help you achieve wellness and fitness goals. For example, in a preliminary 2019 study at the University of Alabama, a group of 40 people age 60 or older who were at risk for heart disease were recruited to participate in an exercise program. All received counseling about fitness, which included advice about how to increase their daily physical activity level in addition to their formal exercise sessions. Half of the participants received a Fitbit, the popular wristwatch-like activity tracker, which counts steps and can be programmed to remind users to get up and move about periodically. The study found that people in both groups exercised the same amount, yet Fitbit users got nearly 2,000 more steps per day, since they spent less nonexercise time sitting down. Tests showed that blood pressure dropped more among the Fitbit users, too.
Other studies suggest that using activity trackers spurs people to be more active. “At a minimum, wearables can help people maintain and manage their fitness portfolio,” says cardiac electrophysiologist Mintu Turakhia, MD, who develops and studies wearable health devices and is executive director of the Stanford University Center for Digital Health. “Tracking your activity, seeing how your fitness has improved, and getting nudges to stand up, exercise, and sleep more — all can have a major impact on overall wellness.”
But why? How do wearables increase physical activity? “They give you real-time feedback,” says public health expert Daniel Fuller, PhD, who studies wearable devices and holds the Canada Research Chair in Population Physical Activity at Memorial University in Newfoundland, Canada. For example, if your daily fitness plan is to take 10,000 steps and a glance at your Fitbit shows that you have barely topped 8,000, you immediately know you have not hit your target. “But we need to react to the feedback and create strategies to actually get to that goal,” says Fuller, such as decide to walk a few more blocks. “That’s the hard part. The watch can’t do it for you.”
New Roles for Smartwatches?
Whether or not smartwatches can help you manage aspects of your health beyond increasing physical activity remains unknown. That hasn’t stopped manufacturers from introducing all kinds of new tools. For instance, some smartwatches now have sensors that monitor blood oxygen levels, a metric that has become of great interest recently, since low oxygen could be a sign of COVID-19, even among people who aren’t experiencing symptoms. Wristbands that monitor blood pressure are available, and models that track blood sugar are on the way.
Yet scientists and doctors are still trying to figure out what role these new wearables can play in managing disease. “First, we need to find out if these technologies improve clinical outcomes, such as preventing heart disease or its complications,” Turakhia says. “And we need to think about how to integrate these technologies not just into your life, but into your daily health care, in a smart and efficient way.”
Early evidence suggests that wearables could play a role in detecting and managing serious health conditions. Turakhia was the senior author of the Apple Heart Study, which examined whether the Apple Watch can spot when a person is having irregular heartbeat, giving a notification that he or she should consult a doctor. The same sensor in the watch that measures heart rate can also detect an erratic pulse, which can be a sign of atrial fibrillation (AFib), an irregular heartbeat that increases the risk for blood clots, strokes, and other heart-related complications.
This investigation included 419,297 people who had not previously been diagnosed with heart rhythm problems. In the study, the Apple Watch detected irregular heartbeat in a small number of participants, and 84% were found to have AFib at the time the notification was sent. (A larger follow-up study is underway.) Turakhia, who treats heart rhythm problems, now uses data collected on patients’ smartwatches as part of his overall approach to managing their conditions.
Smart Clothing and Beyond
Garments worn on the body make up another category of wearable health devices, and they range from potentially life-saving tools to products that may raise an eyebrow.
At one end of the spectrum is the LifeVest, an FDA-approved wearable defibrillator for people at risk for sudden cardiac death (SCD), which occurs when the heart abruptly stops beating or can’t beat hard enough to supply blood to the body. The LifeVest has electrodes that monitor heart rhythm; if a monitor worn on the waist detects a rapid heart rhythm, LifeVest delivers a shock intended to restore a normal pace. Some patients who are at risk for SCD due to heart rhythm problems use LifeVest for protection while awaiting an implanted defibrillator, but the device is also an option for those who are not candidates for implants.
You can even buy “smart” clothing that’s equipped with sensors that monitor you while you work out and give you feedback about your performance through a mobile app.
Meanwhile, a wide range of other wearable health devices are in various stages of development. They include:
- A wearable dialysis device for people with kidney failure.
- A device worn on the wrist that warns people who have had melanoma that they’re getting too much sun.
- Wearable sensors that can help doctors diagnose and monitor Parkinson’s disease.
How Accurate and Secure Are They?
If you decide to try out a wearable health device such as an activity tracker, you may wonder: How accurate are they? “Overall, the devices do pretty well,” says Fuller, who oversaw the largest scientific review of wearables for measuring steps, heart rate, and calorie burning, which was published in the journal JMIR mHealth and uHealth in September 2020. When tested in lab conditions, smartwatches as a group count steps within 3% accuracy, Fuller and his colleagues found, though when scientists have tested them in the “real world” their counts have tended to be somewhat less accurate. What’s more, Fuller found that some brands do a better job than others at measuring heart rate. And none accurately measured calorie burning, so you may not want to use the reading on your smartwatch to decide if it’s OK to have a second cookie.
Since wearables transmit data wirelessly to apps on smartphones and to cloud servers (where health care providers can retrieve data), you might wonder whether your privacy is protected. Could your health data be used for unintended purposes? “The majority of providers have made clear that patients’ data are protected and are not shared with third parties,” says Eleftheria Kouri, a consumer technologies research analyst at ABI research, a technology market advisory firm.
For some users, wearable health devices offer a fun addition to their daily health regimen. “I really enjoy using OsteoBoost,” says Brandi Andrade, an actor and college professor, who uses it for 30 minutes a day. “It’s like getting a bonus workout.” Andrade’s last evaluation for osteoporosis indicated that her bone health had improved. It’s not clear whether OsteoBoost gets the credit, since she takes other measures to strengthen her bones, such as receiving hormone therapy and exercising. But Andrade’s positive medical report has convinced her to stick with the device. “I was thrilled,” she says, “so let’s keep the good vibes going.”