Impact of placement of fitbit HR under laboratory and free-living conditions

Abstract

Wrist-worn activity monitors have become accessible for measuring physical activities, but an activity monitor's accuracy worn at different placements is not well understood. This study aimed to examine the differences in measurements of heart rates, step counts, and calories estimated from the fitness tracker worn at different locations and the accuracy of Fitbit HR against criterion measures. Thirty-two healthy adults participated in this study. Participants wore Fitbit HR at four different locations (right proximal, distal, and left proximal, distal). Treadmill exercise consisted of five 5-min phases including slow walking and jogging. Free-living activities involved ten 5-min activities with four different intensities. We found that the placement of Fitbit HR has no significant influence on the measurement outcomes overall. However, significant differences were observed in the step counts between left and right while climbing stairs (p = 0.003) and sports activities (p < 0.001). The accuracy of Fitbit HR measurements against the criterion measure was moderate. However, we found out that Fitbit HR overestimated the calories regardless of their positions and activity types. In conclusion, the different placements of Fitbit HR do not have a significant influence on the measurements and Fitbit HR was moderately associated with criterion reference devices for measures of heart rate and steps.