How Accurate Are Fitness Monitors? (Article)

toutmonpossible

New York Times Well Blog Post on 16-person study on accuracy of fitness monitors.

"Nate Meckes recognized that he needed to study the accuracy of activity monitors after wearing one. A shipment of the devices, known technically as accelerometers and designed to measure a person’s movement and energy expenditure, had arrived at Arizona State University, where Dr. Meckes was a researcher. To ensure they were operational, he slipped one over his hip and wore it throughout the day, including to an interminable meeting where he stood up and paced. “I’m not good at sitting still,” he says.

Checking his monitor afterward, though, he was flabbergasted. “It had recorded that I was not moving at all,” says Dr. Meckes, now an assistant professor at Azusa Pacific University in Azusa, Calif. The experience inspired him to set up an experiment examining how reliable such devices are.

Until recently, accelerometers, which use electronics to determine bodily movement and intensity, had been confined to research laboratories. But now, at-home users can choose from a variety of devices, sold under such brand names as Fitbit and Nike+ FuelBand. Some are worn on the hip; others on the arm or wrist. All sense movement and feed data into the device’s electronic brain, where proprietary equations determine how much energy someone is expending, meaning, in practical terms, how many calories they burn.

But by and large, users have had to take such measurements on faith. Unbiased, comparative studies of the devices haven’t been available. ..."





http://well.blogs.nytimes.com/2013/06/12/how-accurate-are-fitness-monitors/

davemunger

Thanks for the link! Take-home message seems to be that the monitors aren't as good as they should be at detecting the difference between sitting and standing, and they give too much credit for arm-movement, which underestimates calorie expenditure for things like cycling but overestimates for things like typing.

nilbogger

I'd rather have my FitBit underestimating my calories than overestimating.