Interpersonal influence on physical activity : mediation by psychological factors and moderation by personal characteristics

The primary purpose of the study was to identify relationships among sources of interpersonal influence, putative psychological mediators, and physical activity. The moderation of these relationships by age, body composition, and educational attainment was also evaluated. Responses from 1224 employees were collected through an online survey at a major healthcare facility in central Texas. Structural equation modeling was used to construct the Social Context Scale of Interpersonal Influence and to estimate its ability to explain intention to be physically active and predict physical activity behavior. Invariance testing provided estimates of moderation by age, education, and body composition. Home social context was positively associated with self-efficacy and positive anticipated outcomes and negatively associated with negative anticipated outcomes. Friend social context was positively associated with self-efficacy, positive anticipated outcomes, and intention. Teasing was positively associated with negative anticipated outcomes. Self-efficacy and positive anticipated outcomes were positively associated with intention. Negative anticipated outcomes were negatively associated with intention. The relationship between friend social context and both positive anticipated outcomes and intention was stronger for obese than non-obese respondents. Home social context was more strongly associated with self-efficacy for those with four year degrees than for those without. Self-efficacy was more strongly associated with intention for those with four year degrees than for those without. Self-efficacy predicted subsequent total leisure time physical activity and the relationship was stronger for respondents over 45 years of age than for those younger than 45. The association between self-efficacy and subsequent total leisure time physical activity was also stronger for respondents with a four year degree than for those without. Home and friend social contexts provide potential conduits for post intervention influence on physical activity behavior. The discussion of the benefits of physical activity among friends may encourage overweight and obese individuals considering exercise, especially those with limited physical activity experiences of their own.