The Accuracy of the Detection of Body Postures and Movements Using a Physical Activity Monitor in People after a Stroke

Background: In stroke rehabilitation not only are the levels of physical activity important, but body postures and movements performed during one's daily-life are also important. This information is provided by a new one-sensor accelerometer that is commercially available, low-cost, and user-friendly. The present study examines the accuracy of this activity monitor (Activ8) in detecting several classes of body postures and movements in people after a stroke. Methods: Twenty-five people after a stroke participated in an activity protocol with either basic activities or daily-life activities performed in a laboratory and/or at home. Participants wore an Activ8 on their less-affected thigh. The primary outcome was the difference in registered time for the merged class "upright position" (standing/walking/running) between the Activ8 and the video recording (the reference method). Secondary analyses focused on classes other than "upright position". Results: The Activ8 underestimated the merged class "upright position" by 3.8% (775 s). The secondary analyses showed an overestimation of "lying/sitting" (4.5% (569 s)) and of "cycling" (6.5% (206 s)). The differences were lowest for basic activities in the laboratory and highest for daily-life activities at home. Conclusions: The Activ8 is sufficiently accurate in detecting different classes of body postures and movements of people after a stroke during basic activities and daily-life activities in a laboratory and/or at home.