Effectiveness, Moderators and Mediators of Self-regulation Intervention on Older Adults’ Exercise Behavior: a Randomized, Controlled Crossover Trial

BACKGROUND: Although self-regulation interventions are effective in promoting exercise behaviors, moderators and mediators of interventions among older adults are not well established. This study aimed to examine whether (1) self-regulation intervention promoted exercise behavior, (2) health literacy and habit strength moderated the intervention effect, and (3) self-regulation and habit strength mediated the intervention effect among older adults. METHODS: This study was a randomized, non-blinded, controlled crossover trial. The baseline questionnaire survey assessed the average amount of exercise time per day, self-regulation, habit strength, health literacy, and socio-demographic factors. After the baseline survey, 393 community-dwelling older adults were randomly assigned to either the immediate intervention or the delayed intervention group. For the immediate group, print-based materials were provided once a week for 7 weeks before a second questionnaire survey. For the delayed group, the materials were provided only after the second survey. Finally, a third survey was conducted for both groups. RESULTS: The mixed models showed that the average exercise time was increased after the intervention in both groups. Multiple regression analyses revealed that no factor moderated the intervention effect. From the path analyses, the mediating effect of self-regulation on the relationship between intervention and changes in average exercise time was supported, but the mediating role of habit strength was not clearly indicated. CONCLUSIONS: Although the mediating roles of habit strength for the intervention effects are still inconclusive, self-regulation intervention can promote exercise behavior among older adults, regardless of their health literacy level, habit strength, and socio-demographic characteristics. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s12529-021-10049-3.