Wearable fitness tracking devices may be more convenient than lugging a smartphone along on a jog or trip to the gym, but new research suggests they aren't more accurate than mobile apps that perform similar functions.

In a study published Tuesday in JAMA, researchers revealed that the most popular and top-selling fitness trackers were no more accurate than common smartphone apps, many of them free. Scientists compared the two approaches (tracker versus app) by loading up treadmill users with two smartphones -- one in each pocket, with one running three apps and the other running one -- as well as a number of tracking devices around their wrists and two on their waists.

The 14 study participants, all students at the University of Pennsylvania, were made to walk on a treadmill for 500 and 1,500 steps. The process was repeated once, making for 56 total trials. After each trial, the steps counted by each device and app were recorded. While no one approach is perfect, all but one of the apps and devices were relatively accurate.

"In this study, we wanted to address one of the challenges with using wearable devices: they must be accurate," explained lead study author Meredith A. Case, a medical student at Penn. "After all, if a device is going to be effective at monitoring -- and potentially changing -- behavior, individuals have to be able to trust the data."

"We found that smartphone apps are just as accurate as wearable devices for tracking physical activity," Case added.

Dr. Mitesh Patel, a teacher and researcher at the University of Pennsylvania's Center for Health Incentives and Behavioral Economics at the Leonard Davis Institute, said fitness tracking devices may be useful for getting people off the couch and onto their feet. But he said that a device alone is not enough to motivate someone to stick with an exercise regimen.

"In terms of actually changing people's behavior, there needs to be more than just using the device," he told the Los Angeles Times. "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."