Determining pathways of effect between correlates and outcomes of transport-related physical activity at differing timepoints across the lifecourse: A structural equation modelling approach.

Transport-related physical activity levels differ across the lifecourse; however, the nature of these differences is poorly understood. This study examined the relationship between correlates of transport-related physical activity and how they differ in strength, pathway, and direction across the lifecourse. Structural Equation Modelling assessed relationships between correlates (e.g., age, smoking, education) and transport-related physical activity (assessed via the International Physical Activity Questionnaire) at four timepoints of the Australian Childhood Determinants of Adult Health study: childhood (7-15y; n = 6302), early-adulthood (26-36y; n = 2700), early/mid-adulthood (31-41y; n = 1649), and mid-adulthood (36-49y; n = 1794). Several pathways were consistent across the lifecourse. Self-rated health directly associated with transport-related physical activity across all timepoints. During adulthood greater body mass index and smoking frequency were indirectly associated with lower levels of transport-related physical activity via self-rated health; similarly, lower educated adults, who smoked more frequently, and had poorer health, had lower transport-related physical activity. Urban residence was directly associated with greater transport-related physical activity in childhood and early-adulthood; having more children in early/mid- and mid-adulthood was directly associated with less transport-related physical activity. This is the first study to report pathways of direct and indirect association between correlates and transport-related physical activity at key lifecourse stages. The pathways highlighted can inform policy and practice to aid in the development of age-specific lifecourse interventions.