Background
Web‐based, theory‐driven interventions effectively promote older adults’ physical activity. Social‐cognitive mechanisms of their effect on stage of change need to be further researched.
Methods
Older adults were randomly allocated to intervention group 1 (10‐week online physical activity program), intervention group 2 (same program plus activity tracker), or delayed intervention control group; n = 351 were analyzed (59.6% of originally allocated individuals). Stages of change for recommended endurance and strength training and social‐cognitive predictors of physical activity were assessed using questionnaires at baseline and follow‐up. Intervention effects and mediation were investigated using mixed‐effects ANOVA and ordinal least squares regression.
Results
Direct effects on stage of change were found for intervention group 1 regarding endurance training (bintervention group 1 = 0.44, 95% confidence interval [0.15, 0.73]), and both groups regarding strength training (bintervention group 1 = 1.02, [0.71, 1.33], bintervention group 2 = 1.24, [0.92, 1.56]). Social‐cognitive predictor changes in task self‐efficacy, intention, and action planning explained intervention effect on stage of change, but not to the full extent.
Conclusions
The results indicate significant web‐based intervention effects on physical activity stage, partly mediated by changes in task self‐efficacy, intention, and action planning.