Kayes, Nicola M., Schluter, Philip J., McPherson, Kathryn M., Leete, Marta, Mawston, Grant, and Taylor, Denise
Abstract: Kayes NM, Schluter PJ, McPherson KM, Leete M, Mawston G, Taylor D. Exploring Actical accelerometers as an objective measure of physical activity in people with multiple sclerosis. Objective: To assess the feasibility, acceptability, and psychometric properties of Actical accelerometers in people with multiple sclerosis (MS). Design: Participants attended 2 testing sessions 7 days apart in which they completed 6 activities ranging in intensity while wearing an Actical accelerometer and Polar heart rate monitor. Perceived exertion was recorded after each activity. Setting: University research center. Participants: People (N=31) with a definite diagnosis of MS were purposefully selected, aiming for diversity in level of reported disability, age, sex, and type of MS. Interventions: Not applicable. Main Outcome Measures: Actical accelerometer, Polar S810i and RS800sd heart rate monitors, Borg rating of perceived exertion, six-minute walk test (6MWT), 30-second chair stand test. Results: Accelerometers had good feasibility and acceptability in people with MS. Test-retest reliability was poor for sedentary and free-living activities, with low to moderate intraclass correlation coefficients (.00–.75), but was better for more vigorous or rhythmic activities (.85–.90). Bland-Altman 95% limits of agreement for average accelerometer counts were wide, ranging from ±16 (newspaper reading) to ±1330 (6MWT). Validity was not established with 95% prediction intervals showing high variability for all activities. Conclusions: The psychometric problems highlighted here suggest Actical accelerometers should be used with caution in people with MS as a measure of physical activity, particularly when measuring comparatively sedentary or free-living activities. [Copyright &y& Elsevier]