The criteria one uses to reduce accelerometer data can profoundly influence the interpretation of research outcomes. The purpose of this study was to examine the influence of 3 different interruption periods (i.e., 20, 30, and 60 min) on the amount of data retained for analyses and estimates of sedentary time among older adults. Older adults (N = 311, Mage = 71.1) wore an accelerometer for 7 d and reported wear time on an accelerometer log. Accelerometer data were downloaded and scored using 20-, 30-, and 60-min interruption periods. Estimates of wear time, derived using each interruption period, were compared with self-reported wear time, and descriptive statistics were used to compare estimates of sedentary time. Results showed a longer interruption period (i.e., 60 min) yields the largest sample size and the closest approximation of self-reported wear time. A short interruption period (i.e., 20 min) is likely to underestimate sedentary time among older adults.
Mailey is with the Dept. of Kinesiology, Kansas State University, Manhattan, KS. Gothe, Wójcicki, Szabo, Olson, Mullen, Fanning, Motl, and McAuley are with the Dept. of Kinesiology and Community Health, University of Illinois, Urbana, IL.