BACKGROUND. For preschool children, physical activity is associated with improved measures of health, while sedentary behaviour is associated with less favourable health outcomes. This study updates estimates of physical activity and sedentary behaviour among children aged3 to 5, based on combined data from two cycles of the Canadian Health Measures Survey (CHMS) in order to calculate adherence to Canadianphysical activity and sedentary behaviour guidelines. DATA AND METHODS. The data are from two independent samples that comprised the 2009-to-2011 (cycle 2) and 2012/2013 (cycle 3) CHMS. Accelerometry and a parent-administered questionnaire were used in both cycles on children aged 3 to 5. Accelerometer data, collected in 60-second epochs in cycle 2 and in 15-second epochs in cycle 3, were combined using an adjustment factor derived in an independent sample. Prevalence of adherence to the physical activity guidelines, according to the accelerometer data, was estimated based on a Betabinomial distribution. Adherence to the screen-time component of the sedentary behaviour guidelines was calculated using parent reports. Results are presented by personal and household-related covariates. RESULTS. An estimated 73% of 3– to 4-year-olds and 30% of 5-year-olds met their respective physical activity guidelines. Screen-time targets were met by 22% of 3– to 4-year-olds and 76% of 5-year-olds. INTERPRETATION. Because they rely on a larger sample size and stronger estimation methods, the findings of this study are more robust than previously published estimates. Results reveal room for improvement, particularly 5-year-olds’ physical activity and 3– to 4-year-olds’ screen time.
