Performance of a pedometer to measure physical activity in a U.S. cohort with chronic obstructive pulmonary disease

Objective assessment of physical activity (PA) in chronic obstructive pulmonary disease (COPD) is important. We examined the performance of the Omron HJ-720ITC pedometer. A sample of 176 persons with stable COPD wore the Omron and the StepWatch Activity Monitor (SAM) in the clinic and the community. A 4 s step filter in the Omron screens out erroneous intermittent steps; it captures continuous walking that lasts >4 s. The SAM captures all intermittent and continuous steps walked. Omron-steps were compared with manually counted steps in the clinic and with SAM-steps in the community. We calculated the intraclass correlation coefficient for the first 2 d, the first 3 d, etc., up to 14 d. The Omron registered >/= 90% of the manually counted steps from the in-clinic walk in 155 of 176 subjects (88%). In the community, 47 +/- 16% of SAM-steps were continuous ones that were captured by the Omron. For the Omron and the SAM, at least 7 d of monitoring should be used to capture decreases in PA on weekend days and obtain optimum reliability for all Global Initiative for Chronic Obstructive Lung Disease stages. The Omron accurately and reliably measures continuous walking in COPD. The Omron may be ideal for use in PA interventions that promote continuous walking as exercise.