Longitudinal trends in gasoline price and physical activity: The CARDIA study

Objective: To investigate longitudinal associations between community-level gasoline price and physical activity (PA). Method: In the Coronary Artery Risk Development in Young Adults study, 5115 black and white participants aged 18-30 at baseline 1985-86 were recruited from four U.S. cities (Birmingham, Chicago, Minneapolis and Oakland) and followed over time. We used data from 3 follow-up exams: 1992-93, 1995-96, and 2000-01, when the participants were located across 48 states. From questionnaire data, a total PA score was summarized in exercise units (EU) based on intensity and frequency of 13 PA categories. Using Geographic Information Systems, participants' residential locations were linked to county-level inflation-adjusted gasoline price data collected by the Council for Community & Economic Research. We used a random-effect longitudinal regression model to examine associations between time-varying gasoline price and time-varying PA, controlling for age, race, gender, baseline study center, and time-varying education, marital status, household income, county cost of living, county bus fare, census block-group poverty, and urbanicity. Results: Holding all control variables constant, a 25-cent increase in inflation-adjusted gasoline price was significantly associated with an increase of 9.9. EU in total PA (95% CI: 0.8-19.1). Conclusion: Rising prices of gasoline may be associated with an unintended increase in leisure PA.