Why do teens abandon bicycling? A retrospective look at attitudes and behaviors

Obesity is a major health problem in the United States and around the world. To date, relationships between obesity and aspects of the built environment have not been evaluated empirically at the individual level. To evaluate the relationship between the built environment around each participant's place of residence and self-reported travel patterns (walking and time in a car), body mass index (BMI), and obesity for specific gender and ethnicity classifications. Body Mass Index, minutes spent in a car, kilometers walked, age, income, educational attainment, and gender were derived through a travel survey of 10,878 participants in the Atlanta, Georgia region. Objective measures of land use mix, net residential density, and street connectivity were developed within a 1-kilometer network distance of each participant's place of residence. A cross-sectional design was used to associate urban form measures with obesity, BMI, and transportation-related activity when adjusting for sociodemographic covariates. Discrete analyses were conducted across gender and ethnicity. The data were collected between 2000 and 2002 and analysis was conducted in 2004. Land-use mix had the strongest association with obesity (BMI >/= 30 kg/m(2)), with each quartile increase being associated with a 12.2% reduction in the likelihood of obesity across gender and ethnicity. Each additional hour spent in a car per day was associated with a 6% increase in the likelihood of obesity. Conversely, each additional kilometer walked per day was associated with a 4.8% reduction in the likelihood of obesity. As a continuous measure, BMI was significantly associated with urban form for white cohorts. Relationships among urban form, walk distance, and time in a car were stronger among white than black cohorts. Measures of the built environment and travel patterns are important predictors of obesity across gender and ethnicity, yet relationships among the built environment, travel patterns, and weight may vary across gender and ethnicity. Strategies to increase land-use mix and distance walked while reducing time in a car can be effective as health interventions.

Leisure time physical activity is inversely associated with cardiovascular risk, although evidence for the protective effects of active commuting is more limited. The present review examines evidence from prospective epidemiological studies of commuting activity and cardiovascular risk. Meta-analytic procedures were performed to examine the association between commuting physical activity and cardiovascular risk. Several cardiovascular endpoints were examined including mortality, incident coronary heart disease, stroke, hypertension and diabetes. We included eight studies in the overall analysis (173,146 participants) that yielded 15 separate risk ratios (RR). The overall meta-analysis demonstrated a robust protective effect of active commuting on cardiovascular outcomes (integrated RR=0.89, 95% confidence interval 0.81-0.98, p=0.016). However, the protective effects of active commuting were more robust among women (0.87, 0.77-0.98, p=0.02) than in men (0.91, 0.80-1.04, p=0.17). Active commuting that incorporates walking and cycling was associated with an overall 11% reduction in cardiovascular risk, which was more robust among women. Future studies should investigate the reasons for possible gender effects and also examine the importance of commuting activity intensity.

Rising rates of overweight children have focused attention on walking and biking to school as a means to increase children's physical activity levels. Despite this attention, there has been little documentation of trends in school travel over the past 30 years or analysis of what has caused the changes in mode choice for school trips. This article analyzes data from the 1969, 1977, 1983, 1990, 1995, and 2001 National Personal Transportation Survey conducted by the U.S. Department of Transportation to document the proportion of students actively commuting to school in aggregate and by subgroups and analyze the relative influence of trip, child, and household characteristics across survey years. All analyses were done in 2006. The National Personal Transportation Survey data show that in 1969, 40.7% (95% confidence interval [CI]=37.9-43.5) of students walked or biked to school; by 2001, the proportion was 12.9% (95% CI=11.8-13.9). Distance to school has increased over time and may account for half of the decline in active transportation to school. It also has the strongest influence on the decision to walk or bike across survey years. Declining rates of active transportation among school travelers represents a worrisome loss of physical activity. Policymakers should continue to support programs designed to encourage children to walk to school such as Safe Routes to School and the Centers for Disease Control and Prevention's KidsWalk. In addition, officials need to design policies that encourage schools to be placed within neighborhoods to ensure that the distance to school is not beyond an acceptable walking distance.