Does activity space size influence physical activity levels of adolescents?—A GPS study of an urban environment

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: 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 km(2) (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. CONCLUSION: School and school travel are important sources of PA in Vancouver adolescents, irrespective of activity space area covered.