Patterns of sedentary behavior and weight status among children.

To make robust conclusions regarding the association between accelerometer-measured sedentary time and overweight and obesity among children, several gaps in the literature must be addressed. The purpose of this study was to examine associations between sedentary time, weekday sedentary time, weekend sedentary time, sedentary bouts, sedentary breaks, and BMI z-score among children and by low (bottom 50%) and high (top 50%) moderate- to vigorous-intensity physical activity (MVPA) participation. Results are based on 787 children aged 11 years living in Toronto, Canada. Children's physical activity and sedentary time were objectively assessed using ActiGraph accelerometers in 2010/11. Height and weight were measured and BMI z-scores were calculated based on the World Health Organization growth standards. When participants were stratified into low and high MVPA groups, sedentary bouts of 5-9 (β = 0.22 [95% CI: 0.01, 0.43]) and 10-19 (0.30 [-0.05, 0.55]) minutes for total days were associated with BMI z-score in the low MVPA group only. Similar trends were observed with the weekday but not the weekend variables. Therefore, in addition to increasing MVPA, reducing time spent in 5- to 19-min sedentary bouts may have important implications for weight status particularly for children with lower MVPA participation during the week.