A latent growth curve model to estimate electronic screen use patterns amongst adolescents aged 10 to 17 years

Background: High quality, longitudinal data describing young people's screen use across a number of distinct forms of screen activity is missing from the literature. This study tracked multiple screen use activities (passive screen use, gaming, social networking, web searching) amongst 10- to 17-year-old adolescents across 24 months. Methods: This study tracked the screen use of 1948 Australian students in Grade 5 (n = 636), Grade 7 (n = 672), and Grade 9 (n = 640) for 24 months. At approximately six-month intervals, students reported their total screen time as well as time spent on social networking, passive screen use, gaming, and web use. Patterns of screen use were determined using latent growth curve modelling. Results: In the Grades 7 and 9 cohorts, girls generally reported more screen use than boys (by approximately one hour a day), though all cohorts of boys reported more gaming. The different forms of screen use were remarkably stable, though specific cohorts showed change for certain forms of screen activity. Conclusion: These results highlight the diverse nature of adolescent screen use and emphasise the need to consider both grade and sex in future research and policy

Active school transport and weekday physical activity in 9-11 year old children from 12 countries

OBJECTIVES: Active school transport (AST) may increase the time that children spend in physical activity (PA). This study examined relationships between AST and weekday moderate-to-vigorous physical activity (MVPA), light physical activity (LPA), sedentary time (SED) and total activity during naturally organized time periods (daily, before school, during school and after school) in a sample of children from 12 countries. METHODS: The sample included 6224 children aged 9–11 years. PA and sedentary time were objectively measured using Actigraph accelerometers. AST was self-reported by participants. Multilevel generalized linear and logistic regression statistical models were used to determine associations between PA, SED and AST across and within study sites. RESULTS: After adjustment for age, highest parental educational attainment, BMI z-score and accelerometer wear time, children who engaged in AST accumulated significantly more weekday MVPA during all studied time periods and significantly less time in LPA before school compared with children who used motorized transport to school. AST was unrelated to time spent in sedentary behaviors. Across all study sites, AST was associated with 6.0 min (95% confidence interval (CI): 4.7–7.3; P<0.0001) more of weekday MVPA; however, there was some evidence that this differed across study sites (P for interaction=0.06). Significant positive associations were identified within 7 of 12 study sites, with differences ranging from 4.6 min (95% CI: 0.3–8.9; P=0.04, in Canada) to 10.2 min (95% CI: 5.9–14.4; P<0.0001, in Brazil) more of daily MVPA among children who engaged in AST compared with motorized transport. CONCLUSIONS: The present study demonstrated that AST was associated with children spending more time engaged in MVPA throughout the day and less time in LPA before school. AST represents a good behavioral target to increase levels of PA in children