title: Does Activity Space Size Influence Physical Activity Levels of Adolescents? - A GPS study of an urban environment.
abstract: BACKGROUND
  Physical activity (PA) is closely linked with child and youth health, and active travel may be a solution to enhancing PA levels. Activity spaces depict the geographic coverage of one's travel. Little is known about activity spaces and PA in adolescents.
  
  
  OBJECTIVE
  To explore the relation between adolescent travel (using a spatial measure of activity space size) and daily moderate-to-vigorous PA (MVPA), with a focus on school days.
  
  
  METHODS
  In Fall 2012, we used Global Positioning Systems to manually identify trips and generate activity spaces for each person-day; quantified by area for 39 students (13.8±0.6 years, 38% female) attending high school in urban Downtown Vancouver, Canada. We assessed the association between activity space area and MVPA using multi-level regression. We calculated total, school-day and trip-based MVPA for each valid person-day (accelerometry; ≥ 600 min wear time).
  
  
  RESULTS
  On school days, students accrued 68.2 min/day (95% CI 60.4-76.0) of MVPA. Daily activity spaces averaged 2.2 km2(95% CI 1.3-3.0). There was no association between activity space size and school-day MVPA. Students accrued 21.8 min/day (95% CI 19.2-24.4) of MVPA during school hours, 19.4 min/day (95% CI 15.1-23.7) during travel, and 28.3 min/day (95% CI 22.3-34.3) elsewhere.
  
  
  CONCLUSIONS
  School and school travel are important sources of PA in Vancouver adolescents, irrespective of activity space area covered.
authors.affiliation: Centre for Hip Health and Mobility, 7/F - 2635 Laurel Street, Vancouver, BC, Canada V5Z 1M9; Vancouver Fraser Medical Program, Faculty of Medicine, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC, Canada V6T 1Z3.
authors.forename: Nolan C
authors.initials: NC
authors.lastname: Lee
authors.affiliation: Department of Pediatrics, Faculty of Medicine, University of British Columbia, 4480 Oak Street, Vancouver, BC, Canada V6H 3V4.
authors.forename: Christine
authors.initials: C
authors.lastname: Voss
authors.affiliation: Centre for Hip Health and Mobility, 7/F - 2635 Laurel Street, Vancouver, BC, Canada V5Z 1M9.
authors.forename: Amanda D
authors.initials: AD
authors.lastname: Frazer
authors.affiliation: Centre for Hip Health and Mobility, 7/F - 2635 Laurel Street, Vancouver, BC, Canada V5Z 1M9; Carolina Population Center, University of North Carolina at Chapel Hill, 206 West Franklin St, Chapel Hill, NC, USA 27516.
authors.forename: Jana A
authors.initials: JA
authors.lastname: Hirsch
authors.affiliation: Departments of Family Practice and Orthopaedics, Faculty of Medicine, University of British Columbia, 3114 - 910 West 10th Avenue Vancouver, BC, Canada V5Z 1M9.
authors.forename: Heather A
authors.initials: HA
authors.lastname: McKay
authors.affiliation: Centre for Hip Health and Mobility, 7/F - 2635 Laurel Street, Vancouver, BC, Canada V5Z 1M9; Faculty of Health Sciences, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada V5A 1S6.
authors.forename: Meghan
authors.initials: M
authors.lastname: Winters
keywords: Activity space; Adolescent; Health promotion; Physical activity; Spatial behavior; Transportation