UNC study determines effectiveness of physical fitness trackers

The Gillings School of Global Public Health partnered with the research institute RTI International to see if Fitbits and other activity trackers are truly accurate. 

The study found these devices were most accurate when counting steps and less reliable when measuring sleep quality.

Robert Furberg, a clinical informaticist and research technologist at RTI, co-authored the study. 

 “At the end of the day, the devices may not be 100 percent accurate all of the time, but in cases where researchers ... don’t need a really high level of precision, these devices really do hold a lot of promise for people who are looking to measure physical activity over time or look for changes in physical activity in people over time,” Furberg said.

Furberg said he also learned people show enthusiasm for wearable technology like Fitbits.

“It is not every day that as a researcher, you discover that your primary data collection instrument is a desirable object that people have already integrated in their lives,” Furberg said.

Dr. Kelly Evenson, a research professor of epidemiology at the Gillings School, led the study as part of the University Scholars Program at RTI International. 

Evenson was matched up with Robert Furberg’s project at RTI International because their work complemented each other, Furberg said.

“Given her background as a physical activity epidemiologist, and given my interest in censor-based, passive, longitudinal data collection using smart phone applications or different kinds of wearables or implantable devices, it seemed to be a natural fit," he said. "She is interested in measuring the behavior, and I am interested in kind of measuring anything.” 

Evenson said they decided to study the validity of these products after realizing no one had tested them before. She began the study unsure of the accuracy of the trackers, but her research proved their validity.

“If you had asked before the review, I would have said they probably aren’t quite so good, but they really are.”

The University Scholars Program at RTI allows faculty members at universities with institutional history with RTI, like UNC and Duke University, to collaborate with researchers for a year. The faculty members are selected through an application process and then matched to a project. 

Evenson and Furberg plan to continue working together and are looking to continue their research with physical activity trackers.

Sandra Martin, the associate dean for research at the Gillings School of Global Public Health, said the relationship between the Gillings School and RTI created a collaborative experience for the study. 

“We are going more and more towards team science, where there are so many specialties now and so many interesting public health problems that it really helps to have a team approach with different types of specialists on it," she said.

Martin said the research completed in the school is used to inform public health programs and improve public health. 

“We want to make sure that our research is not something that just gets published in a journal and sits on a shelf and gets dusty," she said. "We want to make sure people are using it to really improve the health of the public.” 

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