Physical activity and child health: Can school-based intervention make a difference?

AbstractChildhood obesity and inactivity is a significant public health problem that also has economic consequences. Therefore, economists have a role to play in determining the causal impacts. The influences of childhood background on outcomes can, usefully, be broken down into the effect of family, school and peer. To combat the raising childhood obesity, schools have been advocated as a potential area. This paper analyses whether increasing physical activity in a school context can contribute to health improvement using multiple outcomes. We address the issue by using a unique longitudinal data set of, respectively, 1087 (BMI) and 1047 (fitness) schoolchildren attending 37 state schools in the Municipality of Aalborg, Denmark. The effect is identified by using a randomized experiment that creates an exogenous increase in physical activity. Surprisingly, we find that the intervention did not have the expected impact on schoolchildren’s health, and the scant evidence we have points towards a negative effect. A plausible explanation is that the results mask important heterogeneity. Another plausible explanation is that the results also capture any compensating behaviour that schoolchildren engage in by being less active out of school. From a public-policy perspective, increasing physical activity in a school context seems to increase the ‘gap’ in child health and ‘crowd-out’ outside-school physical activity. Consequently, a supportive cost-benefit case might exist if parental behaviour is assumed to be affected by school resources and endogenous