Objective: To examine how "travel by walking" before and after school contributes to total physical activity of adolescent girls.
Design: Cross-sectional sample.
Setting: Thirty-six middle schools from Arizona, Maryland, Minnesota, Louisiana, California, and South Carolina participating in the Trial of Activity for Adolescent Girls (TAAG).
Participants: Seventeen hundred twenty-one sixth-grade girls consented to participate; adequate information was available for 1596 participants (93%).
Main exposure: Travel by walking before school, after school, and before and after school combined assessed from the 3-Day Physical Activity Recall.
Main outcome measure: Mean minutes of physical activity measured by accelerometry were estimated for total physical activity (light, moderate, vigorous), moderate to vigorous activity (MVPA), and MVPA of 3 metabolic equivalents.
Results: Travel by walking was reported by 14% of participants before school and 18% after school. Girls who reported travel by walking before and after school (combined) had 13.7 more minutes (95% confidence interval, 1.2-26.3) of total physical activity and 4.7 more minutes (95% confidence interval, 2.2-7.2) of MVPA than girls who did not report this activity. Before-school and after-school walkers (but not both) accumulated 2.5 more minutes (95% confidence interval, 0.10-4.9) and 2.2 more minutes (95% confidence interval, 0.24-4.2) of MVPA on an average weekday, respectively, than nonwalkers.
Conclusion: Our results provide evidence that walking to and from school increases weekday minutes of total physical activity and MVPA for middle-school girls.