摘要：Objectives. We sought to determine whether the socioeconomic environment was associated with no participation in physical activity among adolescents in Boston, Massachusetts. Methods. We used cross-sectional data from 1878 urban adolescents living in 38 neighborhoods who participated in the 2008 Boston Youth Survey, a biennial survey of high school students (aged 14–19 years). We used multilevel multiple regression models to determine the association between neighborhood-level exposures of economic deprivation, social fragmentation, social cohesion, danger and disorder, and students’ reports of no participation in physical activity in the previous week. Results. High social fragmentation within the residential neighborhood was associated with an increased likelihood of being inactive (odds ratio = 1.53; 95% confidence interval = 1.14, 2.05). No other neighborhood exposures were associated with physical inactivity. Conclusions. Social fragmentation might be an important correlate of physical inactivity among youths living in urban settings. Interventions might be needed to assist youths living in unstable neighborhoods to be physically active. Physical activity is important to the growth and development of children and adolescents. 1,2 Physical activity is associated with a decreased risk for overweight and obesity, type 2 diabetes, and other chronic morbidities. 1–3 Recent recommendations for physical activity among children and adolescents aged 6 to 17 years include at least 1 hour a day of moderate to vigorous physical activity. 3 However, research indicates that only 8% of American adolescents meet these recommendations. 4 In 2011, in the United States, 13.8% of students had not participated in at least 60 minutes of physical activity that increased their heart rate and made them breathe hard some of the time on any day during the 7 days before the survey. 5 A better understanding of factors that may influence physical inactivity is warranted. Although individual and familial characteristics are known to be determinants, 6–12 growing evidence suggests that physical activity is associated with the socioeconomic environment. 13–17 The residential neighborhood, where children spend large portions of their time, may influence their health behaviors. Socioeconomic features of the neighborhood have been shown to be associated with adolescent physical activity. Area-level economic deprivation, which is a collective measure of average socioeconomic position of populations living within a particular area, 13,17,18 is one such neighborhood characteristic that may influence health behavior. Economic deprivation may be an indication of the distribution of environmental resources and exposures at the area level. Previous work has shown economic deprivation as a significant predictor of physical activity levels. 13,17 Social fragmentation, a dimension of the socioeconomic environment that is conceptually distinct from economic deprivation, is linked to the concept of anomie, which Emile Durkheim defined as a state of normlessness, 19 or the breakdown of social bonds between individuals and their communities, with fragmentation of social identity and rejection of self-regulatory values. 19 Instead of being a proxy for poverty, social fragmentation is an indication of rapid population turnover, single-person households, and rented tenancy, which are thought to be related to greater residential instability. Researchers have used census variables, such as the proportion of residents renting, to define specific social conditions. It is hypothesized that social fragmentation leads inhabitants to feel disconnected with their neighbors and their community. This might influence parents to disallow their youths to participate in forms of physical activity such as active transportation to school or work. In a previous study, we found an association between social fragmentation and walking for exercise among mothers of children who are at risk for obesity. 20 Other area-level characteristics that have been shown to be associated with physical activity behavior include social cohesion, 14 disorder, 15 and neighborhood safety. 15,21 Social cohesion has been defined as the connectedness and solidarity among individuals and groups in society. 22 Neighborhood disorder is composed of both social and physical disorder. 23 Social disorder involves the presence of threatening individuals or groups, and physical disorder is defined by the deterioration of urban landscapes. 23 Neighborhood safety has been measured objectively (e.g., crime rates 24–26 ) and by respondents’ perception of their neighborhoods. 15,27–31 In the present study, we tested potential pathways through which neighborhood socioeconomics could influence youths’ physical inactivity. First, we examined the potential mediation of the association between each of the neighborhood socioeconomic characteristics and physical inactivity via perceptions of neighborhood safety. For example, a neighborhood that is characterized by high social fragmentation, low social cohesion, high crime rates, high poverty, and high physical disorder might elicit feelings of fear and perceptions of lack of safety. As a result, parents may be less likely to allow their children to use active modes of transportation or play outside. This is supported by numerous studies showing that youths who perceive their neighborhoods to be unsafe are more likely to be physically inactive. 15,32,33 A second possible pathway is represented by neighborhood differences in the level of individual-level social cohesion; i.e., communities with high levels of social fragmentation or high economic deprivation are also characterized by lower levels of cohesion between residents. In turn, an erosion of social cohesion is associated with physical inactivity because residents lack the effective means for the transmission of norms that encourage exercise among youths, 34,35 or they lack the collective efficacy to maintain the local physical infrastructure for physical activity (e.g., parks and playgrounds). 36 The additive role of independent area-level socioeconomic factors has not been fully investigated. Also, the mechanisms in which socioenvironmental characteristics influence physical activity need to be better understood. Therefore, the objective of this investigation was to determine the association between neighborhood economic deprivation, social fragmentation, safety, and social disorder on physical inactivity among a sample of public high-school students in Boston, Massachusetts. We also investigated perception of neighborhood safety and student-reported social cohesion as mediators between socioeconomic characteristics and physical activity.
