The economics of physical activity: societal trends and rationales for interventions.

What are Americans doing with their time and their money and what has changed in recent decades? Do changes suggest interventions that will lead to healthier lifestyles? This paper analyzes several different data sets that reveal some surprising (and some less surprising) insights. The big growth areas, both in terms of expenditure and time allocation, have been leisure time and travel/transportation. Leisure-time industries outpace gross-domestic-product growth for both "active" (sporting goods, dance studios, gyms) and "sedentary" industries (spectator sports, cable TV), although industries associated with more sedentary lifestyles grow the fastest. Overall time spent in productive activities, whether at home or work, has declined by several hours each week for both men and women compared to 40 years ago. Reduced physical activity by itself is not a reason for intervening, as many changes improved overall quality of life (even if not necessarily health-related quality of life). But other trends are more likely to reflect poorly functioning markets, leading to worse economic and health outcomes. Market failures that lead to less physical activity or unhealthy nutrition justify interventions, both from an economic and a public health perspective.