Testing the MASS model: Motivation, affect, social support and self -efficacy as predictors of exercise behaviors

Much research has been done to identify the optimal set of factors that allow for the best prediction or explanation of health behavior change, yet there is concern that the health behavior field is not moving forward due to a lack of comparison between the numerous health theories. In addition, no models of health behavior exist that address the cognitive, affective, and social aspects of exercise in one cohesive framework. The current study aimed to address these issues by testing the utility of the theory of planned behavior (TPB) and self-determination theory (SDT) for predicting exercise intentions and behavior. Further, a model containing intrinsic motivation, affect, social support, and self-efficacy (MASS model) was tested for its predictive validity in regards to motivation for engaging in healthy eating and exercise behaviors beyond the effects of the TPB and SDT. The main hypothesis was that the MASS model would account for a significant portion of the variance in exercise intentions and behavior, beyond the effects of the TPB and SDT.;Results indicated that the TPB and SDT models accounted for more of the variance in intentions to exercise and eat healthy, particularly the constructs of attitudes and perceived competence than the MASS model. However, when predicting actual exercise behaviors, the affect component of the MASS model accounted for a statistically significant portion of the variance beyond the effects of the TPB and SDT.;Engaging in physical activity involves a complex interaction between biological, environmental, social, and psychological influences. Findings from the present research suggest that affect may be a stronger predictor of exercise behavior. Emphasis is placed on the need to continue identifying the best theories and models for studying health behaviors.;Keywords: exercise behaviors, intentions, comparing health theories, theory of planned behavior, self-determination theory.;Three hundred and twenty five adults from undergraduate psychology courses, university fitness classes, and fitness centers in the community completed an initial survey containing items from the TPB measure, SDT measure, and the MASS model measure, as well as questions on demographics. Two hundred and thirty participants (response rate: 70%) completed the Week 1 follow-up survey and one hundred and thirty seven (response rate: 42%) completed the Week 3 follow-up.