The impact of parenthood on Canadians' objectively measured physical activity: an examination of cross-sectional population-based data.

BACKGROUND: Parenthood has been associated with declines in leisure-time exercise and moderate-to-vigorous physical activity (MVPA), but less is known about its impact on sedentary time and light-intensity activity. Although the health benefits of MVPA are well established, a growing body of research has been showing that even after controlling for MVPA levels, a detrimental dose-response association exists between sedentary time and adverse health outcomes and a beneficial dose-response association exists for light-intensity activity. METHODS: This study examined the impact of parenthood, the number of children in the home, and the age of the youngest child on objectively measured physical activity (i.e., accelerometer derived daily minutes of sedentary, light, and MVPA) among a nationally representative cross-sectional sample of 2234 men and women who participated in the 2009-2011 Canadian Health Measures Survey. RESULTS: After controlling for sociodemographic variables, ANCOVAs indicated that parents engaged in more light activity but less MVPA than non-parents and women whose youngest child was aged 12-15 years were more sedentary than women without children. Among both men and women, having a child <6 years of age in the home was associated with the greatest amount of light activity and lowest MVPA. CONCLUSIONS: Modest differences emerged between the physical activity level of parents and non-parents for both genders and across intensity levels. In general, parenthood was associated with less MVPA and more light-intensity activity, and more differences emerged among women compared to men. More research is needed before conclusions can be drawn regarding the health consequences of these differences.