Consumer-Based Activity Trackers as a Tool for Physical Activity Monitoring in Epidemiological Studies During the COVID-19 Pandemic: Development and Usability Study (Preprint)

Abstract

BACKGROUND Consumer-based physical activity trackers increase in popularity. The widespread use of these devices and the long-term nature of the recorded data provides a valuable source of physical activity data for epidemiological research. Major challenges include the large number of activity tracker providers and models, and the difference in how and what data are recorded and shared. OBJECTIVE The aim of this study was to develop a system to record data on physical activity from different providers of consumer-based activity trackers, and to examine its usability as a tool for physical activity monitoring in epidemiological research. The longitudinal nature of the data and the concurrent pandemic outbreak allowed us to show how the system can be used for surveillance of physical activity levels before, during, and after a COVID-19 lockdown. METHODS We developed a system (mSpider) for automatic recording of data on physical activity from participants wearing activity trackers from Apple, Fitbit, Garmin, Oura, Polar, Samsung, and Withings, as well as trackers storing data in Google Fit and Apple Health. To test the system throughout development, we recruited 35 volunteers to wear a provided activity tracker from primo 2019 and onwards. In addition, we recruited 113 participants with privately owned activity trackers worn before, during, and after the COVID-19 lockdown in Norway. We examined monthly change in number of steps, minutes of moderate-to-vigorous physical activity, and activity energy expenditure during 2019-2020 using bar plots and two-sided paired sample t-tests and Wilcoxon signed-rank test. RESULTS Compared to March 2019, there was a significant reduction in mean step count and mean activity energy expenditure during the March 2020 lockdown period. The reduction was temporary, and the year to year comparison show a small increase in moderate-to-vigorous physical activity and no change in steps and activity energy expenditure. CONCLUSIONS mSpider is a working prototype currently able to record physical activity data from providers of consumer-based activity trackers. The system was successfully used to examine change in physical activity levels during the COVID-19 period.