Intentions, planning, and self-efficacy predict physical activity in Chinese and Polish adolescents: Two moderated mediation analyses1

Planning is assumed to translate intentions into health behaviors. However, this may fail due to a lack of perceived self-efficacy. People do not tackle challenging tasks if they harbor self-doubts, even if they have made a good action plan. The present two descriptive longitudinal studies are designed to examine the putative moderating role of self-efficacy in the planning-behavior relationship. In Study I (N = 534 Chinese adolescents), intentions were assessed at baseline, whereas planning, self-efficacy, and physical activity were measured four weeks later. In Study II, 620 Polish adolescents filled out questionnaires assessing physical activity, intentions, planning, and selfefficacy with a 10-week follow-up assessment of physical activity. A moderated mediation model was examined. Planning was specified as a mediator between intentions and behavior, whereas self-efficacy was specified as a moderator of the planningbehavior relationship. Results confirm that levels of self-efficacy moderate the mediation process. The strength of the mediated effect (intention via planning on behavior) increased along with levels of self-efficacy. These results remained valid after accounting for baseline physical activity. For planning to mediate the intention-behavior relation, adolescents must have sufficiently high levels of self-efficacy. Otherwise, planning 1 The preparation of this paper was partially supported by Grant N106 036 32/2487 (Scientific Funds in years 2007-10) from the Ministry of Science and Higher Education in Poland. 2 Correspondence: Trauma, Health, & Hazards Center. University of Colorado at Colorado Springs. 1420 Austin Bluffs Pkwy. Colorado Springs. CO 80933-7150 (USA). E-mail: [email protected]