Investigating active transportation to and from school : identification of predictors and health benefits

Rationale: Evidence from the past 20 years points to important secular declines in physical activity. Researchers point to this decline as a factor in the increase in overweight and obesity among children. Active transportation (AT), defined as non-motorized modes of transportation such as walking or cycling to/from school, is one potential opportunity for physical activity. Previous studies have conceptual and methodological shortcomings thus limiting our understanding of the phenomenon.    Objective:  The overarching goals of the thesis are to identify individual and ecologic determinants of AT and to evaluate the possible health benefits of AT. Four investigations address the following specific objectives: (1) To describe the proportion of children who walked, used public transit, were driven to school in a school bus or vehicle, or used multiple transportation modes to and from school in a population-based sample of children and adolescents living in Quebec, Canada. (2) To identify correlates of AT to and from school among children and youth in a population-based sample of children and adolescents living in Quebec, Canada.  (3) To identify time-varying and time-invariant individual and ecologic determinants of AT to/from school across the school years in population-based samples of Quebec and Canadian children.  (4) To examine the relationship between AT to and from school with change in body mass index (BMI) from kindergarten to grade 2 in a population-based sample of Quebec children.    Methods:  Three population-based samples of youth were used to address these objectives, including the 1999 Quebec Child and Adolescent Health and Social Survey (QCAHS), the Canadian National Longitudinal Study of Children and Youth (NLSCY), and the Quebec Longitudinal Study of Child Development (QLSCD). Longitudinal analyses techniques were applied.   Results: Analyses show four sets of findings. 1) According to the QCAHS, children who were 9 years old, living in urban areas, and were from low household income families were significantly more likely to use AT to/from school.  2)  Findings from the NLSCY study indicated that the time-varying predictors: living in a household with insufficient income, living in a household with only one parent, having an older sibling in the household, and living in an urban setting were associated with greater likelihood of using AT to/from school.  3) With the use of QLSCD, patterns of AT to/from school across time, were identified including children who were from insufficient income households, and residing in economically deprived neighbourhoods. These results indicate that children who are the most underprivileged and exposed to environments not conducive for AT are those most likely to use AT to/from school suggesting the presence of  environmental injustice.  4) Finally, the BMI of children who use AT to/from school consistently from Kindergarten to Grade 2 espoused a more healthy trajectory in comparison to that of children who did not use sustained AT to/from school.    Conclusion:  Although AT to/from school may prove to be favourable to the health of children, as manifested through healthful changes in BMI across time, routes to school need to be safe in order for all children to benefit from this behaviour.  Replication studies that use measures of neighbourhood dangerosity that go beyond self-report, natural experiments, and inclusion of large representative samples from urban areas are needed.

Keyphrases: active transportation to/from school, walking, cycling, environmental injustice, longitudinal analysis, population based cohorts