TMI, Apple Watch! Why you don’t really need all that data.

Not all data is good or useful, say doctors, exercise physiologists and coaches, and having more data doesn’t mean you need more effective training. The real questions are not about the wearable, but about the wearer.

What are wearables?

A wearable is a tracking device worn on your body that measures one or more bodily functions, whether heart rate, sleep time, step count, or breathing. Most, like those from Fitbit, Garmin, Coros, Whoop, and Oura, are not considered medical devices and are not regulated or evaluated by the Food and Drug Administration. Indeed, recently the FDA warned consumers that wearable devices that claim to measure or estimate blood sugar levels without piercing the skin should not be used to treat diabetes.

Regardless, many devices contain metrics that are typically collected in a laboratory setting.

For example, a measurement that can be useful for athletes is your VO2 max, the maximum amount of oxygen your body can use during intense exercise. The number is usually determined in a laboratory by exercising at different intensities while wearing a mask that records oxygen consumption and carbon dioxide production. However, wearables claim to derive this number using an equation based on your heart rate, which should be taken with a grain of salt, experts say.

Other data, such as number of steps and distance traveled, are generally more accurate.

Can they motivate you to exercise more?

“Activity trackers are facilitators, not instigators, of behavior change,” says David R. Bassett, Jr., professor emeritus of kinesiology, recreation and sport studies at the University of Tennessee at Knoxville.

In other words, the device alone won’t make your workouts easier or improve your sleep cycles. But they can help you identify trends in your exercise regimen and track your progress as you try to improve.