Motion Sensor Use for Physical Activity Data: Methodological Considerations

BackgroundPhysical inactivity continues to be a major risk factor for cardiovascular disease, and only one half of adults in the United States meet physical activity (PA) goals. PA data are often collected for surveillance or for measuring change after an intervention. One of the challenges in PA research is quantifying exactly how much and what type of PA is taking place—especially because self-report instruments have inconsistent validity. ObjectiveThe purpose is to review the elements to consider when collecting PA data via motion sensors, including the difference between PA and exercise, type of data to collect, choosing the device, length of time to monitor PA, instructions to the participants, and interpretation of the data. MethodsThe current literature on motion sensor research was reviewed and synthesized to summarize relevant considerations when using a motion sensor to collect PA data. ResultsExercise is a division of PA that is structured, planned, and repetitive. Pedometer data include steps taken and calculated distance and energy expenditure. Accelerometer data include activity counts and intensity. The device chosen depends on desired data, cost, validity, and ease of use. Reactivity to the device may influence the duration of data collection. Instructions to participants may vary depending on the purpose of the study. Experts suggest pedometer data be reported as steps—because that is the direct output—and distance traveled and energy expenditure are estimated values. Accelerometer count data may be analyzed to provide information on time spent in moderate or vigorous activity. DiscussionThoughtful decision making about PA data collection using motion sensor devices is needed to advance nursing science.