Out-of-School Sports Time and Children’s Body Weight Status: Evidence from a Longitudinal Survey

We used data from the Child Development Supplement (CDS) of the Panel Study of Income Dynamics in 2002 and 2007 to examine the relationship between the specific sport time spent during weekdays or weekends and American children’s body mass index (BMI). Time spent on out-of-school sports was recorded on a randomly selected weekday and a weekend day. Sports were further categorized as formal (organized sports such as sports games or lessons) or casual (any unorganized sports such as sports time in the neighborhood). Child’s height and weight were measured in person by interviewers. Body mass index was used to measure the child’s body weight status. We applied ordinary least square and fixed effects regressions to examine the cross-sectional and longitudinal relationships between out-of-school sports time and children’s body weight status. Children’s socio-demographics and parental socioeconomic status were controlled in the analyses.  Double time spent on out-of-school sports during weekdays from 2002 to 2007 was associated with a reduction of BMI by 0.14 units, but the effects of time spent on out-of-school sports during weekends did not achieve statistical significance. For boys and girls, time spent on weekday casual (formal) sports was associated with a reduction of BMI by 0.18 and 0.17 units, respectively.  Time spent on out-of-school sports during weekdays was more significant than during weekends in reducing BMI among US children.