As I am typing this, a device rests on my wrist that purports to unlock a trove of real-time information about my body’s performance. I can click a button and check my heart rate and review how much it’s varied over the course of the day. It can tell me how many steps I’ve taken, how many minutes I’ve been “active” throughout the day, and — if I wore it while I slept — just how well I rested, according to the data its sensors can pick up from my arm.
The Apple Watch is a remarkable piece of technology, when you stop and really think about what it does. It’s no surprise, perhaps, then, that we have collectively become obsessed with these things. One 2023 government survey found that one in three Americans wear a smartwatch or wristband to track their health and fitness. More recent industry surveys put that figure even higher: More than half of the US population owns a wearable or connected device and tracks at least one health metric with it.
That’s a lot of people who are swimming in the ocean of information that our Apple Watches, and FitBits, and Oura Rings, and Whoops report back to us. Dr. Michael Joyner, who studies the physiology of exercise at the Mayo Clinic, said he has a three-pronged criteria for thinking about the usefulness of these metrics: Is it measurable? Is what you’re measuring actually meaningful? And is the information that you’re receiving actually actionable?
“If one or two are missing, the thing may be the most interesting thing in the world. It may be cool,” he said. “But it’s not going to make a difference in long-term outcomes.”
Across medicine, we are developing remarkable tools for detecting things in the human body, outpacing our ability to interpret what we are finding. We are getting closer to a future where these devices could offer invaluable insights into how our body is performing outside of the doctor’s office or hospital, but here in the present, we should keep our expectations in check.
Here’s what you should know about some of the most common metrics that wearables track.
