Combining the Theory of Planned Behaviour and Temporal Self-Regulation Theory to Explore Physical Activity Engagement

Objectives: Consistent physical activity is important for reducing poor physical and mental health outcomes. Despite being aware of the benefits of physical activity, many people struggle to engage regularly. Various strategies have been suggested to improve an individual’s adherence to physical activity, including, time-of-day preference (i.e., morningness/eveningness). The current study aims to apply constructs from the theory of planned behaviour and temporal self-regulation theory to predict physical activity engagement, with additional predictors of enjoyment and morningness/eveningness. Methods: A prospective design was used to collect data from 228 participants, at two time points, seven days apart. Two hierarchical multiple regressions were used to examine the relationship between the predictor variables and physical activity engagement. Results: Individuals with greater perceived behavioural control had stronger intentions to be physically active, while past engagement, environmental cues, and habit (automaticity) directly predicted physical activity engagement. However, morningness/eveningness and enjoyment were not significant predictors. Conclusion: This study combined theories to predict physical activity engagement, while morningness/eveningness did not predict physical activity engagement, the study underscores the importance of perceived control, habit, and cues. These insights can help tailor interventions, emphasizing factors like automaticity and past behaviour to promote sustained physical activity.