Applying an extended version of the Theory of Planned Behaviour to understand exercise behaviour after leaving university

Regular exercise is an important component of a healthy lifestyle; however, the majority of the UK population does not adhere to recommended weekly exercise. Exercise peaks in the 16-24 age group and declines with age. Life transitions have been found to negatively impact health behaviours such as exercise. The theory of planned behaviour (TPB) was employed to examine the effects of a life transition (graduating university) on exercise intentions and behaviour. The TPB states that the most proximal determinant of behaviour is intention. Intention, in turn, is determined by attitude, subjective norms and perceived behavioural control. Study 1a investigated graduating university students’ beliefs about exercise post-university. First, final year students (N = 11) completed an online belief elicitation questionnaire to identify modal salient beliefs about exercise after leaving university. Fifteen modal salient beliefs were identified (focusing on advantages, disadvantages, significant referents, facilitators, and inhibitors). The strength of these beliefs were then assessed in an online survey of final year students (N = 136) and related to exercise intentions and behaviour six and 18 months after leaving university. Study 1b used the same sample (N = 136) to apply an extended version of the TPB to explain exercise intentions and behaviour post-university. Attitude, intention, planning, and self-identity were all important predictors of exercise intention and behaviour. Study 2 comprised semi-structured telephone interviews with 10 participants, six months after they had left university. The interviews were thematically analysed to provide an in-depth exploration of how and why the transition impacted on exercise beliefs and behaviour post-university. Self-identity, social motivation, routine, and planning were identified as important factors for maintaining exercise behaviour. Study 3 (N = 125) evaluated a brief video-based online intervention, based on the results of Studies 1 and 2, to promote exercise post-university. Final year students were randomly allocated to either a control or intervention condition and followed-up six months later. The effect of the intervention on behaviour was non-significant; however, it had a positive effect on subjective norms at six-month follow-up. The present thesis provides some support for an extended version of the TPB for predicting exercise intentions and behaviour across the transition of graduating university; however, the thesis does not support its utility in the design of a brief online intervention. Further investigation into interventions targeting exercise beliefs, intention, and behaviour across significant life transitions is needed to prevent negative impacts on exercise behaviour.