Physical Activity

Economic and Policy Factors

This policy paper from the National Bureau of Economic Research examines factors contributing to obesity, such as physical inactivity. Data are taken from surveys conducted as part of the 2000–2005 Behavioral Risk Factor Surveillance System (BRFSS) survey. Economic analyses of costs of physical inactivity are complex, because people with sedentary lifestyles have higher annual medical costs, but lower life expectancies. One analysis calculated that using a 5 percent rate of discount for future dollars—the lifetime subsidy from others to those with sedentary lifestyles—was estimated at $1,900 per person.

Although obesity in the United States is increasing, and most people still do not meet federal guidelines for physical activity levels, analyses of recent trends show that Americans have increased activity levels since 1988. To better understand factors that may be influencing time spent on physical activity, the authors use models to explore issues such as opportunity costs of time; environmental variables, such as availability of parks and crime rates; transportation costs and availability; and whether other health behaviors substitute for or contribute to physical activity levels. Three levels of leisure time physical activity–any exercise, physical activity that is moderate or vigorous, and vigorous physical activity—are explored in the models.

Results include that income has a strong positive effect on physical activity, as does education; Hispanic individuals, particularly in low-income groups, are less likely to exercise, and being married generally decreases physical activity. Working people are less likely to exercise than retired or unemployed people, but an individual is more likely to be physically active when unemployment in the county is low. Obesity is generally negatively associated with physical activity. Policy implications of these, and other results, are strong. For example, policies aimed at increasing education can have an effect on activity levels. Similarly, since time constraints play an important role in exercising, policies allowing for job-site exercise and increased access to childcare could be significant in increasing activity levels. More research is warranted, in particular, on interactions between other behaviors such as smoking and drinking, and exercise, as these relationships appear to be complex and multifactorial.

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