Consistent with existing evidence [10
] we found that increased local area PA outlets are associated with higher levels of PA. However, parents who are active, and in turn encourage or influence their children to be more active, may choose to live in neighborhoods that have more PA outlets and should be examined further in future research.
Contrary to existing evidence, which also controlled for neighborhood income/SES [7
] we found no association between the presence of parks and sports fields and increased PA or reduced weight. Studies that found an association between outdoor PA settings and increased PA [7
] targeted younger age groups. These types of settings may be less important for PA in older youth. Recent research [27
] found that park users are primarily children and adults, and that less than 20 percent are adolescents, with more males than females utilizing parks. By simultaneously accounting for multiple measures of the built environment, we are able to assess which environmental measures may have the greatest impact on PA behavior, and may also explain why our findings are inconsistent with previous research. The outdoor PA settings scale is limited in the amount of information it captures. Information on students’ proximity to these settings or on the features of these settings—such as number, type, and condition of playing fields—may have a greater impact on PA than presence alone. This scale is an aggregate measure of these settings, which may bias the estimated effect of our models towards the null making our results more conservative.
Lower levels of neighborhood safety were associated with decreased PA, higher prevalence of obesity and higher BMI. Results showed that perceptions of feeling safe going to and from school are associated with PA. Although our perceived safety measure does not specifically ask about PA, it provides a general indicator of adolescent perceived safety. Previous research [5
] found no association between perceived safety and youth PA. Only one of these studies [15
] asked youth specifically about neighborhood safety; this study was conducted in Portugal and the findings may be less relevant for our sample population. Results of interaction effects by gender suggest that perceptions of feeling unsafe going to and from school was associated with greater decreased PA among females across all three outcome variables. This suggests perceived safety is more important for females and may also help to explain why females engage in more indoor physical activities.
We found an association between the level of physical disorder present neighborhoods and decreased sports participation, increased prevalence of obesity and higher BMI. The effects of the physical disorder scale across our outcome variables were somewhat attenuated when the neighborhood median household income measure was added to the models (results not shown). These results imply that some of the correlation between physical disorder and PA and obesity can be attributed to greater presence of these conditions in low-income neighborhoods.
Consistent with previous research [6
] we found more compact neighborhoods were associated with lower prevalence of obesity and lower levels of BMI. Neighborhoods characterized as being walkable, or more compact, have also been shown to be associated with adolescent PA [19
]. This, coupled with our finding that the presence of bike paths is associated with lower prevalence of obesity and BMI, supports the idea that neighborhoods that are more walkable and bikeable help to increase PA and lower weight. These findings suggest that policies designed to promote more walkable and bikeable communities may have a positive health impact on youth.
More compact neighborhoods were also associated with decreased sports participation. Recent evidence [31
] suggests that people living in more compact neighborhoods may substitute different forms of PA (i.e., walking for utilitarian purposes) based on their location, whereas people living in less compact areas may participate more in sports activities. Our finding that students have higher levels of sports participation in less compact neighborhoods may be related to this substitution effect. Alternatively, this may be a reflection that PA venues for youth are different than those for adults. Although our outdoor PA settings scale picks up the presence of sports fields, it does not capture information on the number of venues available in relation to population or size of the area, nor does it capture what types of sports fields or how many were present in the communities. More sprawling areas would have more space for sports fields, which may be more important PA outlets for 8th
graders than walkable compact neighborhoods. There may also be more school and community-based sports programs offered or accessible (i.e., affordable) to youth in more sprawling (i.e., suburban/rural) than urban areas. However, utilitarian walking, the kind that occurs frequently in compact neighborhoods, was not measured in this study. These findings should be investigated further in future research.
Contrary to prior research [32
] we found no relationship between traffic danger and the PA measures or weight outcomes. This measure may be more important for leisure and utilitarian walking, and biking to reach PA-related facilities and other neighborhood destinations, but less important for other forms of PA.
Consistent with previous research [33
] the results of our random intercept models show the majority of the variance across our outcome measures lies within and not between communities with the environmental measures accounting for 1–2 percent of the total variance in PA and weight. The small magnitude of these effects may in part be due to some of the environmental measures being limited in the amount of information they capture. Again this suggests additional research with more refined environmental measures is needed. Further, community-level variables in general cannot explain much variance in youth outcomes when much of the variance in the outcomes is within communities.