Longitudinal levels and bouts of objectively measured sedentary time among young Australian children in the HAPPY study

Objectives: To examine differences in sedentary time and bouts during and outside of childcare/school periods, and changes in sedentary time and bouts over 1-year among children who remained in childcare (childcare subsample) and among those who transitioned to school (school transition subsample). Design: Longitudinal study. Methods: Results are based on 177 children aged 3-5 years at baseline from the Healthy Active Preschool and Primary Years study in Melbourne, Australia. Sedentary time and sedentary bouts (1-4, 5-9, >= 10 min) for total days and during/outside of childcare/school on weekdays were accelerometer-derived at baseline (2008) and 1-year follow-up (2009), when 57% of participants had transitioned to school. Repeated measures ANCOVAs adjusting for wear time were conducted. Results: Compared to the outside of childcare/school period, children in the school transition subsample spent more time (0.5 min/day or 0.9%wear time) in >= 10 min sedentary bouts at baseline, participated in 26 more min/day of sedentary time at follow-up, and all participants spent less time (2-16 min/day or 2-3% of wear time) in 5-9 min sedentary bouts at baseline and follow-up during the childcare/school period (P < 0.05). Increases in sedentary time (34-54 min/day or 2-3% wear time) and time spent in 1-4 min sedentary bouts (18-29 min/day or 1-2% of wear time) were observed from baseline to follow-up in both the total sample and school transition sub-sample, for total days and during the childcare/school period (P < 0.05). Conclusions: School transition was marked by increased sedentary time. School practices, policies, and environments to reduce sedentary time should be explored. (C) 2015 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.