Problem: A positive affective response is associated with increased participation in voluntary exercise, but the mechanisms by which this occurs are not well known. Consistent with a Theory of Planned Behavior perspective, we tested whether affective response to exercise leads to greater motivation in terms of attitudes, subjective norms, self-efficacy and intentions to exercise. We were also specifically interested in whether a positive affective response leads to more temporally stable intentions. Method: Participants (N = 127) self-reported Theory of Planned Behavior constructs and exercise behavior at baseline and three months later, and provided reports of exercise-related affect during a 30-minute bout of moderate intensity treadmill exercise at baseline. Results: We show that participants who experience greater improvements in positive affect, negative affect and fatigue during exercise tended to report more positive attitudes, exercise self-efficacy and intentions to exercise three months later. Affective response was not predictive of subjective norms. As hypothesized, positive affective response was associated with more stable intentions over time. Conclusions: We conclude that a positive affective response to acute bouts of exercise can aid in building and sustaining exercise motivation over time. (C) 2009 Elsevier Ltd. All rights reserved.
