De Bruijn, G.-J., Verkooijen, K., Van den Putte, B., & De Vries, N. K. (2012). Antecedents of self-identity and consequences for action control: An application of the theory of planned behaviour in the exercise domain. Psychology of Sport and Exercise. 13, 771-778. doi:10.1016/j.psychsport.2012.05.008

Objectives: To study whether exercise action control profiles should be usefully extended to include exercise identity. Further, this study investigated theory of planned behaviour antecedents of exercise identity.
Design: Prospective data from 413 undergraduate students (M age = 21.4; 73.5% females).
Method: Validated questionnaires were used at baseline and follow-up two weeks later to assess exercise behaviour, intention, self-identity, and theory of planned behaviour concepts. Research questions were analysed using chi-square analysis, discriminant function analysis and structural equation modelling. Results were interpreted using p-values and effect sizes.
Results: There was a higher proportion of exercise intenders in the strong exercise identity group than in the weak exercise identity group (81.9% vs. 14.5%) and a higher proportion of successful intenders in the high exercise identity group than in the low exercise identity group (45.5% vs. 18.2%). Affective attitude and perceived behavioural control (PBC) were the most important predictors of exercise action control. Regarding the antecedents of identity, results showed significant and small-sized associations for baseline affective attitude and perceived behavioural control and large-sized association for baseline self-identity.
Conclusion: Exercise identity should be usefully employed to understand exercise motivation and action control. Affective attitude and perceived behavioural control facilitate action control and exercise identity development and are suggested to be taken into account when developing exercise interventions.