Accelerometer-based Sedentary Behavior Assessment

The short period to measure a large sample of children necessitated the use of all available accelerometer models by ActiGraph (7164, LLC, Fort Walton Beach, Florida, USA) in the research groups; (either GT1M, GT3X or ActiTrainer). All accelerometers were worn on the right hip, secured by an elastic waist belt. Accelerometers were initialized using ActiLife software [32 ], selecting a 15-s epoch measurement interval. Children were instructed to wear the accelerometer for seven consecutive days during all waking hours, but to remove it during bathing and other water activities. Minimal wear time was set at eight h/day (i.e. indicating a valid day), and the minimum number of valid days was four [33 (link)]. Non-wear time was defined as 60 minutes or more of consecutive zero counts/min. Total sedentary time was accumulated time below 100 counts/min across all valid days. Sedentary bouts were defined as a period of at least ten consecutive minutes in which accelerometer output was below 100 counts/min. Within these sedentary bouts, zero counts above 100 counts/min were tolerated. Breaks in sitting time were defined as transition in accelerometer count from 100 counts/min to >100 counts/min in between two sedentary bouts [34 (link)].