Relative Contribution of Psychosocial Variables to the Explanation of Physical Activity in Three Population-Based Adult Samples

Background. Despite large differences in physical activity by demographic subgroup, few studies have identified correlates for specific age and sex groups. The present study quantified the unique variance accounted for in each subgroup by the main psychosocial variables. Methods. Three random samples, ages 16–25, 35–45, and 50–65, with a total of 2,390 Belgian subjects, completed psychosocial questionnaires and were interviewed at home. Results. Social influences, self-efficacy, perceived benefits, and perceived barriers varied in importance by age and sex groups. Social variables provided the most unique information about physical activity for all age and sex groups, except older females. Competition was a significant perceived benefit only for young men, whereas health was the most significant perceived benefit for young women. Among older women and men, health concerns were significant perceived barriers to participation in physical activity. Conclusions. The present results provide hypotheses about mediators of physical activity that can be applied in interventions tailored to the needs of various subgroups.