The Mediating Roles of Self-efficacy, Self-regulation, and Preference on the Effect and Maintenance of a Physical Activity Intervention Among Older Adults in China.

backgroundCurrent randomized trial evidence for the mediators of physical activity (PA) intervention mainly focused on short-term outcomes, with little reliable evidence about how to promote longer-term maintenance of PA. Furthermore, whether the mediation effects were consistent across socio-economic status (SES) populations remains unknown. The aim of this study was to examine whether changes in self-efficacy, self-regulation, and preference mediated the intervention effect on PA level using cluster-randomized trial data with follow-up measures at 6 months (short term), 12 months (intermediate term), and 24 months (longer term) in Chinese older adults, and whether such effects were heterogeneous across different SES populations.

methodEight villages were randomly assigned to the intervention (4 villages, n = 238) or the control group (4 villages, n = 267). The intervention group received PA intervention, while the control did not. The hypothesized mediators including self-efficacy, self-regulation, and preference were assessed by valid and reliable scales. The approach used for the mediation analysis was similar to the method described by Baron and Kenny but made use of linear mixed models at each step to account for repeated measurements.

resultsAmong the 505 participants, the mean age was 70.87 (SD, 5.70) years, and 55.2% were female. Changes in preference at 8 weeks mediated the intervention effect on PA level in the short term (mediated, 19.4%) and intermediate term (mediated, 13.9%), while changes in self-efficacy and self-regulation at 4 weeks, 8 weeks, 6 months, and 12 months, as well as changes in preference at 4 weeks and 8 weeks mediated the intervention effect on PA level in the longer term (range mediated, 7.2-27.4%). The mediation effects were more pronounced among those with low SES (range mediated, 9.5-39.6%).

conclusionPreference appeared to be a potential mediator of changes in PA level at the early stages, while self-efficacy, self-regulation, and preference were identified as mediators of maintenance in the longer term in rural older Chinese. Such effects were more pronounced among those with low SES. Future interventions and programs could consider building and strengthening components that target these constructs to make a lasting impact on PA. When developing PA intervention studies, it seems necessary to include strategies tailored according to SES.

trial registrationThe study was registered at the Chinese Clinical Trial Registry, number ChiCTR2100045653. https://www.chictr.org.cn/showprojEN.html?proj=123704 .