An investigation into the development of ACT-based approaches to increase physical activity

It is well documented that regular physical exercise supports physical and mental wellbeing. Despite the promotion of physical activity by world health experts and governments, physical inactivity within the population remains a cause for concern and disorders associated with sedentary lifestyles have continued to increase. Evidence suggests that the uncomfortable private-events people experience during physical exertion can become psychological barriers to participation in physical activity and thus result in avoidant behaviours. Acceptance and commitment therapy (ACT) has been used to promote increased physical exercise by enhancing psychological flexibility in relation to private-events that are perceived as unpleasant. However, relationships between the individual ACT processes and the theories which underpin their use in interventions designed to promote physical activity have yet to be fully explored. Understanding the relationship between ACT processes and physical exercise is key for appropriate and robust intervention development. This thesis aimed to explore the theoretical and practical application of ACT processes in relation to exercise and inform further development of effective brief interventions designed to increase activity levels. The programme of work within this thesis had two phases. The first phase included two studies: a systematic review to explore the existing evidence; and a quantitative survey study to determine if associations exist between physical activity levels and the individual core processes of ACT. Results from phase one found that the reviewed literature failed to explore the use of Relational Frame Theory (RFT) critical to ACT, and a survey suggested that ACT processes of defusion, self-as-context and personal values were likely to play a significant part in activity levels. The second phase comprised of three interrelated quantitative intervention studies designed using RFT. Each explored the ACT processes by measuring task duration and the intensity of private-events experienced during exercise. The first intervention study combined defusion and self-as-context with no significant effects on an exercise task. The second combined defusion, self-as-context and value orientated cues to behaviour change. Exercise duration was significantly increased in the ACT intervention, while there was no decrease in the intensity of private-events. The final study tested a values clarification task with cues to behaviour change and reported significantly increased exercise duration. The thesis demonstrates that relational frame theory applied to ACT processes can influence the duration of exercise although the relationship with private-events remains uncertain. The robust, theory focused approach to this work represents a small but valuable contribution to the development of intervention strategies and has implications for future research. Strategies worked best using a combination of both deictic and hierarchical relations for training cognitive defuison and self-as-context, and especially for the clarification of personal values used as cues to behaviour change. Further research is needed to establish both the external validity and longevity of observed effects