Dancing to a different tune: the predictive utility of the theory of planned behaviour when the behaviour is constrained

Objective: The predictive utility of the Theory of Planned Behaviour (TPB) was tested in a fit, healthy population who were required to exercise regularly. Four physical activity behaviours were examined: one volitional behaviour (dancing) and three activities offered during daily physical training (PT, i.e. running, swimming, team sport).

Method: RAF trainee aircraftsmen (N = 186) completed a questionnaire assessing TPB constructs and past behaviour, followed by a 7-day Physical Activity Recall interview. Participants repeated the behaviour measures one-week later. During the week prior to participation, participants were “free living” and did not have to take PT sessions; during the week between measurement sessions, participants were on base, and so had to complete a compulsory 90 min exercise session, although they were free to choose the specific PT activity.

Results: While intentions were well predicted for all behaviours, the TPB variables explained more of the variance for the volitional behaviour (19.6%) than for constrained behaviours (average 3.5%). Addition of past behaviour resulted in minimal improvement of the existing TPB model of intention and future behaviour for all measured physical activities.

Conclusion: The TPB appears unsuitable for prediction of physical activity when behaviours are constrained by external influences, but appropriate when they are not. Using an assessment of past behaviour during a period when behaviour had different constraints on it than during the period of behaviour being predicted dramatically reduced the contribution of past behaviour compared to previous research.