title: Adolescents' use of the built environment for physical activity.
abstract: BACKGROUND
  Physical activity is a health-enhancing behavior, but few adolescents achieve the recommended levels of moderate-to-vigorous physical activity. Understanding how adolescents use different built environment spaces for physical activity and activity varies by location could help in designing effective interventions to promote moderate-to-vigorous physical activity. The objective of this study was to describe the locations where adolescents engage in physical activity and compare traditional intensity-based measures with continuous activity when describing built environment use patterns among adolescents.
  
  
  METHODS
  Eighty adolescents aged 11-14 years recruited from community health and recreation centers. Adolescents wore accelerometers (Actigraph GT3X) and global positioning system receivers (QStarz BT-Q1000XT) for two separate weeks to record their physical activity levels and locations. Accelerometer data provided a continuous measure of physical activity and intensity-based measures (sedentary time, moderate-to-vigorous physical activity). Physical activity was mapped by land-use classification (home, school, park, playground, streets & sidewalks, other) using geographic information systems and this location-based activity was assessed for both continuous and intensity-based physical activity derived from mixed-effects models which accounted for repeated measures and clustering effects within person, date, school, and town.
  
  
  RESULTS
  Mean daily moderate-to-vigorous physical activity was 22 minutes, mean sedentary time was 134 minutes. Moderate-to-vigorous physical activity occurred in bouts lasting up to 15 minutes. Compared to being at home, being at school, on the streets and sidewalks, in parks, and playgrounds were all associated with greater odds of being in moderate-to-vigorous physical activity and achieving higher overall activity levels. Playground use was associated with the highest physical activity level (β = 172 activity counts per minute, SE = 4, p < 0.0001) and greatest odds of being in moderate-to-vigorous physical activity (odds ratio 8.3, 95% confidence interval 4.8-14.2).
  
  
  CONCLUSIONS
  Adolescents were more likely to engage in physical activity, and achieved their highest physical activity levels, when using built environments located outdoors. Novel objective methods for determining physical activity can provide insight into adolescents' spatial physical activity patterns, which could help guide physical activity interventions. Promoting zoning and health policies that encourage the design and regular use of outdoor spaces may offer another promising opportunity for increasing adolescent physical activity.
authors.affiliation: Massachusetts General Hospital, Boston, MA, USA. noreskovic@mgh.harvard.edu.|Harvard Medical School, Boston, MA, USA. noreskovic@mgh.harvard.edu.
authors.forename: Nicolas M
authors.initials: NM
authors.lastname: Oreskovic
authors.affiliation: Massachusetts General Hospital, Boston, MA, USA. jperrin@mgh.harvard.edu.|Harvard Medical School, Boston, MA, USA. jperrin@mgh.harvard.edu.
authors.forename: James M
authors.initials: JM
authors.lastname: Perrin
authors.affiliation: Massachusetts General Hospital, Boston, MA, USA. arobinson13@mgh.harvard.edu.
authors.forename: Alyssa I
authors.initials: AI
authors.lastname: Robinson
authors.affiliation: Massachusetts General Hospital, Boston, MA, USA. jlocascio@mgh.harvard.edu.|Harvard Medical School, Boston, MA, USA. jlocascio@mgh.harvard.edu.
authors.forename: Joseph J
authors.initials: JJ
authors.lastname: Locascio
authors.affiliation: Harvard Center for Geographic Analysis, Boston, MA, USA. jblossom@cga.harvard.edu.
authors.forename: Jeff
authors.initials: J
authors.lastname: Blossom
authors.affiliation: Massachusetts General Hospital, Boston, MA, USA. mchen1@mgh.harvard.edu.|Harvard Medical School, Boston, MA, USA. mchen1@mgh.harvard.edu.
authors.forename: Minghua L
authors.initials: ML
authors.lastname: Chen
authors.affiliation: Massachusetts General Hospital, Boston, MA, USA. jwinickoff@mgh.harvard.edu.|Harvard Medical School, Boston, MA, USA. jwinickoff@mgh.harvard.edu.
authors.forename: Jonathan P
authors.initials: JP
authors.lastname: Winickoff
authors.affiliation: Harvard Medical School, Boston, MA, USA. alison.field@childrens.harvard.edu.|Boston Children's Hospital, Boston, MA, USA. alison.field@childrens.harvard.edu.
authors.forename: Alison E
authors.initials: AE
authors.lastname: Field
authors.affiliation: Harvard Center for Geographic Analysis, Boston, MA, USA. chloev.green@gmail.com.
authors.forename: Chloe
authors.initials: C
authors.lastname: Green
authors.affiliation: Massachusetts General Hospital, Boston, MA, USA. egoodman3@mgh.harvard.edu.|Harvard Medical School, Boston, MA, USA. egoodman3@mgh.harvard.edu.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Goodman
mesh_terms: D056044:Actigraphy; D000293:Adolescent; D002648:Child; D004779:Environment Design; D015444:Exercise; D005260:Female; D040362:Geographic Information Systems; D015438:Health Behavior; D006801:Humans; D008297:Male; D008404:Massachusetts; D009043:Motor Activity; D012574:Schools; D013997:Time Factors