Changes in social-cognitive variables are associated with stage transitions in physical activity.

When it comes to the adoption or maintenance of physical activity, individuals can be placed along a continuum or into stages of change. The Health Action Process Approach proposes three such stages: non-intentional, intentional and actional. Intraindividual differences are reflected by stage transitions: either progression or regression. The present study examines social-cognitive factors of stage transitions: outcome expectancies, self-efficacy and planning. In an online study on physical activity, 660 adults completed questionnaires at baseline and approximately 3 weeks later. Social-cognitive factors were converted into standardized residual change scores to account for changes in outcome expectancies, self-efficacy and planning within the observation period. Discriminant function analyses revealed stage-specific patterns: progression out of non-intentional stage was associated with self-efficacy increases. Out of intentional stage, regression was correlated with decreases in planning, whereas progression was linked to increases in self-efficacy and planning. Regression from action stage was associated with decreases in self-efficacy. Physical activity promotion should focus on improving self-efficacy for non-intending, intending and acting individuals, whereas planning interventions are recommended for intending individuals. Interventions may be more effective by considering specific mechanisms instead of providing generic interventions for all individuals at different stages.