Abstract
Self-Determination Theory's (SDT) behavioural regulations may be important in explaining the underlying relationship between physical activity (PA) and well-being (e.g., positive affect). Mixed evidence regarding the specific influence of introjected regulation on behavioural persistence and well-being warrants further investigation of its effect on the immediate PA-affect response. In addition, research reveals that PA intensity, which has been associated with PA-induced mood changes, may be linked to one's motivational style. The purpose of this experimental study was to examine the interaction between introjected regulation and Ratings of Perceived Exertion (i.e., intensity; RPE) in predicting changes in positive affect with an acute bout of PA. Fourty-one active adult women engaged in a 30-minute self-paced treadmill run. Situational motivation for running, pre- and post-running positive affect, and RPE were assessed via validated self-report questionnaires. Hierarchical regression analyses revealed a significant interaction effect of RPE and introjection on the change in positive affect from pre- to post-running, ß = -.30, p < .05. At low levels of introjection, the influence of RPE on the change in affect was considerable, with higher RPE ratings being associated with greater increases in positive affect. The need to examine these relationships in association with well-being over the long term, as well as some applied implications of these results, is discussed.
