How Accurate is Your Fitness Tracker?

Recent research suggests popular trackers might not be as accurate as you think

From the Fitbit Flex to Nike’s FuelBand, it’s no secret that fitness trackers have been making a big impact on the world of fitness tech. It seems everyone has given these wearables a shot, hoping to accurately track and then improve on their activity level, steps and sleep. Some people swear by these trackers, while others have deemed them unnecessary and now researchers are confirming what skeptical people have suspected—these wearables aren’t totally accurate.

 While trackers can provide a decent estimate of overall calories burned, a study recently published in the journal Medicine & Science in Sports & Exercise suggests these trackers aren’t as accurate when measuring certain activities, like strength training.

For the study, Researchers at Iowa State University asked 56 people to test the parameters of four major consumer trackers (the Fitbit Flex, Jawbone UP 24, Nike+ FuelBand SE and Misfit Shine) and two research monitors (the BodyMedia Core and Actigraph GT3X+). To mimic real life conditions, the participants were asked to do a sedentary activity, an aerobic activity and then a resistance activity, with five minutes of rest in between each.

“By looking at the most commonly performed activities in exercise and daily living settings, we can examine where the errors occur,” said Yang Bai, lead author and a graduate research assistant in kinesiology. “As expected, some monitors overestimate or underestimate all three activities, but some monitors overestimate one type and underestimate the other two categories, which can cancel out if we don't measure them separately.”

Of the consumer fitness trackers, the Fitbit Flex was most accurate overall, with the lowest error percentage of 16.8 percent. The Misfit Shine didn’t perform well, though, it was the least accurate of the trackers with an error percentage of 30.4. See the complete results below, (graphs courtesy of Iowa State University News Service).

Although this information could be disheartening to those who rely on these trackers, the researchers say that accuracy isn’t the only thing that matters.

“I think the key to a consumer is not so much if the activity monitor is accurate in terms of calories, but whether it’s motivational for them and keeps them accountable for activity in a day,” said Greg Welk, professor of kinesiology.

More Reading:
Do Fitness Trackers Really Work for Weight Loss?
Making the Most of Your Activity Tracker: 5 Simple Steps for Success
How Many Steps Should You Be Taking Each Day? 10 Tips to Help You Meet the Goal