Does the theory of planned behavior mediate the relation between personality and exercise behavior?

Ajzen's (1991) theory of planned behavior (TPB) proposes that the relation between personality and behavior is mediated by the social-cognitive constructs contained within the TPB. The purpose of the present studies was to examine the mediational role of the TPB in the exercise domain using the Five Factor Model (FFM; Costa & McCrae, 1992) as the personality framework. Two studies provided data to answer this question. Study 1 used a cross-sectional design with self-reported exercise behavior from 300 female undergraduate students. Study 2 used a prospective design with objective attendance records from 67 female participants enrolled in structured exercise classes. As expected, extraversion (E), conscientiousness (C), and neuroticism (N) were significantly related to exercise behavior. Contrary to our hypothesis, however, the relation between personality and exercise behavior was only partially mediated by the TPB. Specifically, hierarchical regression analysis of both data sets indicated that E had a direct relation with exercise behavior even after controlling for the TPB. We concluded that personality as operationalized by the FFM may need to be integrated into social-cognitive models applied to exercise behavior. To this end, we suggested that a more sophisticated theoretical description of the relations among personality, the TPB, and exercise behavior is needed.