The primary purpose of this study was to investigate the accuracy of the activPAL physical activity monitor in measuring step number and cadence in older adults. Two pedometers (New-Lifestyles Digi-Walker SW-200 and New-Lifestyles NL-2000) used in clinical practice to count steps were simultaneously evaluated. Observation was the criterion measure. Twenty-one participants (65-87 yr old) recruited from community-based exercise classes walked on a treadmill at 5 speeds (0.67, 0.90, 1.12, 1.33, and 1.56 m/s) and outdoors at 3 self-selected speeds (slow, normal, and fast). The absolute percentage error of the activPAL was <1% for all treadmill and outdoor conditions for measuring steps and cadence. With the exception of the slowest treadmill speed, the NL-2000 error was <2%. The SW-200 was the least accurate device, particularly at slower walking speeds. The activPAL monitor accurately recorded step number and cadence. Combined with its ability to identify primary postures, the activPAL might be a useful and versatile device for measuring activity in older adults.
P. Margaret Grant, Philippa M. Dall, Sarah L. Mitchell and Malcolm H. Granat
Anne Martin, Mhairi McNeill, Victoria Penpraze, Philippa Dall, Malcolm Granat, James Y. Paton and John J. Reilly
The Actigraph is well established for measurement of both physical activity and sedentary behavior in children. The activPAL is being used increasingly in children, though with no published evidence on its use in free-living children to date. The present study compared the two monitors in preschool children. Children (n 23) wore both monitors simultaneously during waking hours for 5.6d and 10h/d. Daily mean percentage of time sedentary (nontranslocation of the trunk) was 74.6 (SD for the Actigraph and 78.9 (SD 4.3) for activPAL. Daily mean percentage of time physically active (light intensity physical activity plus MVPA) was 25.4 (SD for the Actigraph and 21.1 (SD 4.3) for the activPAL. Bland-Altman tests and paired t tests suggested small but statistically significant differences between the two monitors. Actigraph and activPAL estimates of sedentary behavior and physical activity in young children are similar at a group level.
Philippa M. Dall, Dawn A. Skelton, Manon L. Dontje, Elaine H. Coulter, Sally Stewart, Simon R. Cox, Richard J. Shaw, Iva Čukić, Claire F. Fitzsimons, Carolyn A. Greig, Malcolm H. Granat, Geoff Der, Ian J. Deary, Sebastien F.M. Chastin and On behalf of the Seniors USP Team
The Seniors USP (Understanding Sedentary Patterns) study measured sedentary behavior (activPAL3, 9-day wear) in older adults. The measurement protocol had three key characteristics: enabling 24-hour wear (monitor location, waterproofing), minimizing data loss (reducing monitor failure, staff training, communication), and quality assurance (removal by researcher, confidence about wear). Two monitors were not returned; 91% (n = 700) of returned monitors had seven valid days of data. Sources of data loss included monitor failure (n = 11), exclusion after quality assurance (n = 5), early removal for skin irritation (n = 8), or procedural errors (n = 10). Objective measurement of physical activity and sedentary behavior in large studies requires decisional trade-offs between data quantity (collecting representative data) and utility (derived outcomes that reflect actual behavior).