Fitbit Accuracy Depends on Activity Pace and Placement Location

This study is designed to measure the concordance of step counts recorded by Fitbit activity trackers when the devices are placed on multiple locations of the body and while subjects climb stairs at fast, slow, and medium paces. Nine participants wore 5 Fitbit trackers concurrently while performing the stair-climbing activity. The level of concordance was characterized by variability metrics derived from five step counts obtained for each study participant at each climbing pace. Results of one-way ANOVA analysis revealed statistically significant difference between mean variance, standard deviation (SD) and range of step count measurements depending on location of tracker and pace of movement. Stair climbing at a 'medium pace' produced the least variance (25.9±24.5) with smallest SD (4.0±2.3), whereas the 'slow pace' trial produced the greatest variance (1770.9±3307.5) and SD (27.6±27.1). Discordance between Fitbit step count measurements obtained at different activity levels may affect overall accuracy of step count reporting.