Objectives: To predict exercise stage transitions over two consecutive 6-month periods using the theory of planned behaviour (TPB). It was hypothesized that different social cognitive constructs would predict different stage transitions.
Design: Prospective and longitudinal in order to predict multiple stage transitions over time. Assessments were made at baseline, 6 months and 1 year.
Method: Participants were a randomly selected population-based sample of 683 adults who completed two telephone interviews (baseline and 6 months) that assessed exercise stage, intention, perceived behavioural control, attitude, subjective norm, and social support, and a mailed survey (1 year) that assessed exercise stage.
Results: Progression from pre-contemplation was predicted by intention, attitude and subjective norm; progression/regression from contemplation was predicted by intention, perceived behavioural control, attitude, and social support; progression/regression from preparation was predicted by intention and attitude; and regression from action/maintenance was predicted by intention, attitude and social support.
Conclusions: Different social cognitive constructs predicted different stage transitions, which indicates that exercise behaviour change may be represented by a series of stage transitions. Moreover, the TPB may be a useful model for highlighting the key social cognitive constructs that are important for exercise stage transitions.