Poor diet and a lack of physical activity are major factors to the worldwide obesity epidemic, and
make a significant contribution to the overall burden of disease. The determinants of individual
participation in physical activity are not well understood. This paper uses a modified time allocation
framework to explore how economic and demographic factors influence participation in physical
activity. We use data from the first six waves of the Household Income and Labour Dynamics of
Australia survey. The analysis examines frequency of participation in physical activity using both
standard and generalised random effects ordered probit model. We control for individual
heterogeneity as well as exploring differences across gender and employment status. The results
indicate that a rising opportunity cost of participating in physical activity significantly impacts on
participation. Economic and demographic factors have a stronger impact on employed individuals’
participation. This suggests that policies which make exercise more convenient, and hence decrease
the opportunity cost of exercise, will help to encourage more people to participate in physical
activity.