Why do youth high in self-control exercise more? Motivation quality and self-regulatory skills as mediators

Abstract

Aims: Trait self-control (TSC) is associated with physical activity (PA), but less is known of the explanatory mechanisms. We examined whether (1) the TSC-PA relationship is mediated by autonomous motivation (AM) and self-regulatory skills (SRSs), and if (2) TSC moderates the associations between SRSs-PA or AM-PA. Methods: 411 adolescents (aged 17.8) answered a survey with validated measures of TSC, AM, SRSs and PA; PA was measured again after one month. A subsample validated self-reported PA using 7-day accelerometry. Results: TSC was positively associated with AM and SRSs (r’s=.26 to .38). TSC-PA was partially mediated by AM (CI 95% .004, .023), and Action Planning (CI 95% .144, .546]; Coping Planning (CI 95% .198, .654); Self-monitoring (CI 95% .124, .529). TSC did not moderate the relationships between SRSs-PA or AM-PA. Discussion: Although those with high TSC were likely to have higher AM and use more SRSs, the effect of the TSC on PA was mediated by SRTs rather than motivation. Improving motivation quality and imparting planning and self-monitoring skills may be useful for increasing PA regardless level of TSC.