Grant: Doctoral Award - Frederick Banting and Charles Best Canada Graduate Scholarships

Adolescents will be recruited and randomly assigned to four equal groups according to their body weight (healthy weight vs overweight/obese) and the intervention group they will be assigned to (control vs an incidental physical activity plus active commuting lifestyle intervention). Individuals in both "active" groups (healthy weight and overweight + intervention) will receive a program to promote lifestyle-embedded physical activity and reinforcement to walk or bike to school and other destinations daily during a whole school year. The impact of the intervention will be assessed through a series of measures taken at the beginning and the end of the protocol. First, all participants will undergo a test to evaluate their fitness. A nurse will take blood samples to measure blood lipid levels and other indicators of health. Different measures of obesity will also be taken. The students will wear an activity monitor before, during and after the intervention to assess whether the intervention increased daily physical activity. In addition, they will indicate their commuting mode (walking, biking) and the time required to get to and from school in a structured journal. Together, these tools will allow us to determine the impact of the intervention on the volume of physical activity. Information on social and environmental indicators - which could potentially modulate the impact of the intervention - will also be collected through questionnaires and interviews. Finally, the level of adherence and satisfaction with the protocol will be assessed to document the feasibility of such an intervention. The results of this study could provide a better understanding of the impact of active commuting and lifestyle-embedded physical activity upon total physical activity levels in adolescents. These alternative modes of activity, perhaps particularly suited for overweight and obese youth, could be promoted as a way to improve cardiovascular health in this population.