To provide key insight, a new narrative review led by the University of Miami Miller School of Medicine analyzed how physical activity intervention studies utilize the devices. The review, published May 2021 in the Journal of Medical Research, provides scientists with a plethora of information that may inform future trials involving Fitbit devices.

“Given the public appeal, prominence, and relatively low cost of Fitbit devices, researchers are increasingly using them in conjunction with or as a substitute for accelerometers in physical activity intervention studies,” said study lead author Ruth St. Fleur, a Ph.D. in Prevention Science and Community Health candidate in the Miller School of Medicine’s Department of Public Health Sciences.

“We are utilizing Fitbit devices in our family-based lifestyle interventions and wanted more information about how they had been previously utilized in physical activity intervention studies,” said study senior author Sara St. George, assistant professor in the Department of Public Health Sciences. “Given there was no existing synthesis on the topic, we decided a paper like this might be a helpful resource to share with others in the field.”

To conduct the review, authors synthesized and summarized information from 75 existing studies published from 2012 to 2020 that utilized the device. The studies each represented physical activity interventions for children, adolescents, or for early, middle, or older aged individuals.

Co-authors of the review analyzed what kind of devices were utilized in the studies, their intended use, such as whether it was used as an intervention or measurement tool, participant wear instructions, rates of adherence to device wear, strategies used to boost adherence, and the complementary use of other physical activity measures.

The review found that there were considerable differences in the use of Fitbit devices within the existing studies, especially regarding different age groups. The findings include the following:

• Interventions for adults tended to require longer wear periods
• Studies on children and adolescents usually had more limited device wear periods
• Most of the studies that were analyzed used developmentally appropriate behavior change techniques and device wear instructions
• Regardless of the developmental stage and intended Fitbit use, such as measurement or intervention tools, the most common strategies used to enhance wear time in the studies included sending participants reminders through texts or emails and asking them to log their steps or synchronize their Fitbit data daily
• The rates of adherence to the wear time criteria were reported using varying metrics
• Most studies supplemented the use of Fitbit devices with additional objective or self-reported measures for physical activity

According to the review, the differences in Fitbit use across physical activity intervention studies show how novel its use is in the field of research. The review also states that as the use of commercially available wearables continues to expand in physical activity research, the lack of uniformity in study protocols and metrics of reported measures represents a major issue for comparability purposes.

“Our hope is that this review serves as a step in the right direction in terms of identifying best practices for incorporating wearables like Fitbits into future physical activity interventions,” said Dr. St. George.

Researchers note that there is a need for access to information regarding the prospective registration of physical activity intervention studies, such as a clear rationale for the use of several measures, specifying the source of the main physical activity outcome, as well as how additional measures will be used in the context of Fitbit-based interventions.

Co-authors of the narrative review also included University of Miami’s Rafael Leite and Dr. Marissa Kobayashi from the Department of Psychology, Yaray Agosto, M.P.H., from the Miller School of Medicine’s Department of Public Health Sciences, and Dr. Danielle Jake-Schoffman from the University of Florida’s Department of Health, Education, and Behavior.

Written by Amanda Torres

Published on July 19, 2021