Abstract
BackgroundUnderstanding changes in physical activity and sedentary time (SED) during early childhood may provide insights into how to effectively promote a healthy start to life. This study examined changes in total volume and bouts of SED, light- (LPA), and moderate- to vigorous-intensity physical activity (MVPA) across early childhood, and explored differences in change between boys and girls.MethodsData were drawn from 330 children participating in the Melbourne InFANT Program, collected between 2008 and 2013 and analysed in 2017. Children’s physical activity and SED were assessed for at least 7 days at each timepoint using ActiGraph GT1M accelerometers at 19 months, 3.5 and 5 years of age. Total volume of SED (≤100 counts per minute [CPM]), LPA (101–1680 CPM) and MVPA (≥1681 CPM) were expressed as a percentage of wear time, and the frequency (number of bouts/day) and duration (mins/bout) of SED, LPA and MVPA bouts ≥1 min were calculated at each time point. Multilevel models with random intercepts and slopes were used to examine changes in total volume and bouts of SED, LPA and MVPA for boys and girls.ResultsCompared to aged 19 months, children’s total volume of SED and LPA decreased at 3.5 and 5 years old, while MVPA increased. The frequency of SED bouts at 3.5 and 5 years was greater than at 19 months, but the duration was shorter. Additionally, the frequency and duration of LPA bouts was lower and MVPA bout frequency and duration was greater at 3.5 and 5 years. In general, there was no evidence of sex differences in trajectories of children’s physical activity and SED. However, variations in trajectory were observed at the individual child level.ConclusionsChildren’s total volume and bouts of SED, LPA and MVPA change across early childhood, mostly in a favourable direction. Trajectories appear to be similar for boys and girls. Investigation of individual variation in trajectories is likely to provide greater insight into associations between physical activity and future health and behavioural outcomes.
Highlights
Understanding changes in physical activity and sedentary time (SED) during early childhood may provide insights into how to effectively promote a healthy start to life
Twelve percent of children in the sample were attending primary school at the 5 year old time point, there was no evidence that their total volume of SED, light-intensity physical activity (LPA) or moderate- to vigorous-intensity physical activity (MVPA) differed from those who were not attending school
Since the mean duration of MVPA bouts increased only slightly over time, our findings suggest that the higher total volume of MVPA occurring at 3.5 and 5 years resulted from progressively more bouts rather than from more prolonged MVPA
Summary
Understanding changes in physical activity and sedentary time (SED) during early childhood may provide insights into how to effectively promote a healthy start to life. Identifying typical patterns of accumulation of physical activity and sedentary time across early childhood can provide an indication of how physical activity initiatives might be structured at various ages to increase total volume of physical activity and minimise sedentary time, as well as optimise health outcomes for children. Previous studies examining changes in total volume of daily physical activity and sedentary time have generally reported that physical activity declines and sedentary time increases from the age of 4–5 years onwards, likely coinciding with the commencement of formal schooling [4,5,6]. A recent longitudinal study from Switzerland that focused on children from 2.5 years of age found increased total physical activity and moderate-to-vigorous physical activity (MVPA) up to age six, with sedentary time remaining somewhat stable [7]
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