Smartphone apps keep pace with costly fitness trackers

Some smartphone apps proved to be about as accurate at counting steps as several fitness trackers, according to a new study. Updated models, such as those shown here in December, were not tested, and no marks were given for other functions the devices and apps track.
(Bebeto Matthews / Associated Press)

If you’re delaying your walking program to save up for a wearable fitness tracker, the ruse is over. A free app on your smartphone can do the job about as well as some popular wearable devices, a new study has found.

On average, steps counted with free apps strayed only slightly from observed counts and were comparable or better than those tallied by the devices, according to the study published online Tuesday in the Journal of the American Medical Assn.

Still, just about all of the tracking methods proved accurate enough for the average person looking for feedback on exercise, said study co-author Dr. Mitesh Patel, of the University of Pennsylvania’s Center for Health Incentives and Behavioral Economics at the Leonard Davis Institute.

“I think the takeaway was that they’re all pretty accurate,” Patel said. “With the exception of one wearable device that was 20% lower than average, the rest of them were pretty close to the mean. We think for the purposes of the average person who just want to track their steps, all of these, for the most part, will do.”


Researchers got 14 students on the University of Pennsylvania campus to walk a treadmill set for 3 miles per hour, for 500 and 1,500 steps. They did each trial twice, with two smartphones (an iPhone 5s and Galaxy S4) in their pockets, three wearable devices on their wrists and three other devices on their waistbands.

On average, the app-based counters were closer to the mark than the worn devices, but there were differences in reliability across the 56 trials. The study did not rank the devices, nor test other data they track, such as calories consumed.

Fitbit’s One and Zip models were most consistently close to the observed count, while the Yamax Digi-Walker SW-200 was on par with them, with slightly more variability across trials, according to the study.

The Jawbone UP24 and Fitbit Flex came in slightly below the average count and varied more than the apps across trials, while the Nike+ Fuelband was 22.7% off the average and had the widest variation across trials, according to the data.

Fitness devices are far less common than smartphones, which now are the preferred device for two thirds of U.S. cellphone users. A recent market study estimated about one in five U.S. consumers has purchased a fitness tracker, while only about half of them wore it daily.

The device alone may be enough to get some people on their feet, but most will need more motivation to stick with a fitness program, said Patel, who studies behavioral changes.

“In terms of actually changing people’s behavior, there needs to be more than just using the device,” he said. “We have to be able to pair these devices with effective engagement strategies that help people to build new habits and use effective feedback loops.”

Take a few steps toward science. Follow me on Twitter: @LATsciguy