Residential moves, neighbourhood walkability, and physical activity: a longitudinal pilot study in Ontario Canada.

Background: Numerous cross-sectional studies have consistently demonstrated an association between attributes of urban form or 'walkability' and individual- and population-level physical activity (PA) patterns. However, in the absence of longitudinal research, the self-selection problem undermines the claim that a walkable built form produces more physically active people. Through a longitudinal pilot study of 'imminent movers' in Ontario using a quasi-experimental approach, we sought to examine the feasibility of longitudinal methods that would produce stronger evidence for a causal relationship between the built environment and PA levels.