The accuracy of personal activity monitoring devices

Activity monitoring has important applications in orthopaedic and medical research. There is a paucity of information on device accuracy. Thirty adults tested the accuracy of 10 devices in 5 activities: walk 400-M, run 400-M, walk 10-M, ascend and descend 10 steps. A second protocol tested slow walking speeds at 1.0, 1.5, 1.8, and 2.0 MPH. The waist-based devices FitBit One and Omron HJ-321 were >90% accurate for all activities. The wristband devices and Smartphone Apps were <90% accurate for most activities. The StepWatch Activity Monitor was >95% accurate at lower cadence activities, but undercounted running by ~25%. Waist-based, dedicated activity monitors are highly accurate in a variety of activities.