Can Activity Trackers Help with your New Year’s Resolution? SIUE Researchers Examine Accuracy of Popular Devices
January 6, 2015, 4:25 PM
“Their general purpose is to track your activities of daily living,” said Bryan Smith, assistant professor of kinesiology and health education at Southern Illinois University Edwardsville. “How many steps are you taking? It’s hard to get the general population to do 30 minutes of physical activity a day.”
As a researcher and educator, Smith’s goal is to get people active and reach the recommended 10,000 steps per day. It’s clear to Smith; these activity trackers successfully draw people’s attention to their daily step count and activity level.
“When people first put on an activity tracker they often realize how inactive they are,” he explained. “If it’s the middle of the day and my step count is only at 3,000, I know I need to walk down the hall and back so that I get some steps in.”
But are the devices’ measurements accurate?
Smith and former student researcher Kristin Dierker, studied four of the most popular activity tracking devices during the 2013-2014 academic year to answer that question.
Contrary to other research on this topic that measured only short-term accuracy, Smith and Dierker examined how well the devices measured daily activity for a full week.
“People wear these for 24 hours a day, seven days a week, and no one else had asked the question: How accurate are these devices over the course of the day?” Smith explained.
Smith and Dierker’s research analyzed what they considered the four most popular devices at that time: Nike FuelBand, FitBit One, FitBit Flex and Jawbone UP.
Nearly 40 participants wore each of the four activity monitors at the same time. Three were worn on the wrist. The FitBit One was worn on the waist, along with an ActiGraph GT3X+. The Actigraph is a research grade accelerometer that also measures steps. It was used as the standard for comparing the data collected.
Findings indicated two of the four devices were fairly accurate in their measurements. However, the other two greatly overestimated the participant’s data.
“The Nike FuelBand, worn on the wrist, and the FitBit One, worn on the waist, had the best agreement with the Actigraph,” Smith said. “On average, the Nike FuelBand was better than the FitBit One. The other two were not as accurate. They weren’t very good at all.”
Smith attributes the difference in devices to their sensitivity. He noted that both the FitBit Flex and Jawbone UP measure movement during sleep, while the Nike FuelBand does not. Smith believes that sensitivity caused the two devices to pick up extraneous movements of the upper body, leading to overestimated results.
Despite inaccurate measurements on some devices, activity trackers are still worth using, according to Smith.
“I think they’re definitely worth it,” Smith said. “Are they 100% accurate? No, they’re not. But, if it motivates someone to be more physically active over the course of the day, I think it’s doing its job.”
The market is now flooded with activity tracking devices, beyond those tested, with greater capabilities like interfacing with a heart rate monitor. Smith suggests considering the product’s usability and its applications when deciding which device to purchase. He notes that since this research was completed, the Nike FuelBand has been discontinued.
Photo: Bryan Smith, assistant professor of kinesiology and health education.
