title: Rural middle school nutrition and physical activity environments and the change in body mass index during adolescence.
abstract: BACKGROUND
  For rural adolescents, schools are among the few places where environmental interventions can promote health outside of the home. The goal of this study was to assess the nutrition and physical activity (N&PA) environments of schools attended by a birth cohort and examine the association with change in body mass index (BMI) from sixth to eighth grade.
  
  
  METHODS
  Using data from adolescents of a rural New York State birth cohort (N = 281), we used linear mixed models to identify N&PA environments associated with change in BMI. We also examined family income trajectory as a potential modifier to consider how the association between school environment and change in BMI might differ depending on income.
  
  
  RESULTS
  We found considerable heterogeneity in environments within and between schools. Among students with low-income trajectories, reductions in BMI z-scores were associated with school environments that promote better physical education (PE) and general (non-PE, non-sport) physical activity. Schools with better sports environments were associated with reductions in BMI for some students, but not lower-income students.
  
  
  CONCLUSIONS
  School environments may have differing effects on students depending on their socioeconomic status. Strategies are needed to identify and address barriers that impair low-income students' access to health-promoting school resources.
authors.affiliation: Cornell University, Division of Nutritional Sciences, 352 Martha Van Rensselaer Hall, Ithaca, NY 14850.
authors.forename: Margaret
authors.initials: M
authors.lastname: Demment
authors.forename: Nancy
authors.initials: N
authors.lastname: Wells
authors.forename: Christine
authors.initials: C
authors.lastname: Olson
mesh_terms: D000293:Adolescent; D015992:Body Mass Index; D002648:Child; D005260:Female; D005522:Food Services; D006293:Health Promotion; D006801:Humans; D007182:Income; D016014:Linear Models; D008137:Longitudinal Studies; D008297:Male; D009043:Motor Activity; D009518:New York; D018673:Nutrition Policy; D012424:Rural Population; D012572:School Health Services; D012574:Schools; D011795:Surveys and Questionnaires
keywords: BMI z-score; linear mixed models; longitudinal; middle school; nutrition environment; physical activity environment