OP22 Synthesising theoretical evidence on causal pathways by which changes to the environment may act to promote physical activity

Background Interventions to change the built environment offer a promising approach for promoting physical activity and improving health. However, there has been little theoretical consideration of the underlying mechanisms by which such interventions might operate. This systematic review aims first to map the potential causal pathways linking environmental changes with changes in physical activity, and second to review the evidence for specific mechanisms. This presentation will focus on the first, mapping, stage of the review. Methods We used a systematic, transparent and iterative approach, drawing on realist principles. As we were interested in scoping a diverse landscape of theories linking the environment, physical activity and health, we searched seven electronic literature databases representing a range of disciplines (Cochrane, Medline, ProQuest, HealthEvidence, NICE, TRID and Web of Science). Theoretical and conceptual material was extracted from a variety of source documents including review articles, theoretical papers and intervention studies. We used thematic analysis in an in-depth, configurative approach to synthesis, aiming to derive a set of plausible generalisable pathways by which environmental changes could promote changes in physical activity. Results Our initial searches identified 2760 potential sources from fields including public health, sociology, behavioural science, and transport. From these, 79 conceptual and review papers were included. A further 30 papers were found through reference lists, and 26 primary intervention studies were identified. Interventions included the creation or refurbishment of whole neighbourhoods (n = 2), greenspaces or parks (n = 9), trails or paths (n = 11), cycle infrastructure (n = 2), and public transport services (n = 2). The key themes elicited related to social practice, agency and structure, conscious and unconscious processes, and the interdependence of social and physical environments. A set of interlinked potential pathways was identified, linking environmental changes with changes in physical activity through combinations of changes in both attributes and judgements of both physical and social environments, as well as in individual reasoning. Conclusion Mapping these theoretical pathways provides greater understanding of the potential individual and social mechanisms of change. In the second part of the review, we will search for evidence to support or refute specific mechanisms. Assembling this evidence will shed light on why some environmental interventions do or do not ‘work’, how they operate, and in which contexts and population groups they are most effective. This will allow us to refine our understanding and identify promising intervention points and strategies.