Physical activity and posttraumatic stress disorder symptoms: an exploration of cognitive and psychological mechanisms

<p dir="ltr">Over the past decade, physical activity (PA) has gained increasing attention as a complementary approach to alleviating symptoms of posttraumatic stress disorder (PTSD). PTSD is characterised by memory disturbances (e.g., intrusive memories, and overgerenral autobiographical memory), negative alterations in cognition and mood (e.g., impaired executive functioning, decreased positive affect, and increased negative affect), and avoidant behaviours (e.g., reduced PA engagement), all of which collectively diminish individuals’ quality of life in the long term. PA can positively influence these various domains of impairment, addressing physical health, emotional well-being, and cognitive functioning through both direct and indirect pathways. Therefore, the objective of the current program of research is to investigate the therapeutic effects of PA on PTSD and stress symptoms and explore the underlying mechanisms. Specifically, the investigation was conducted across three contexts: in a laboratory setting using stress induction (Phase 1), in a gym setting under experimental conditions (Phase 2), and in daily life when individuals confronted stressful life events (Phase 3). Studies in the three phases will be presented in the following eight chapters. </p><p dir="ltr">Chapter 1 provides an overview of the potential cognitive (specifically, inhibitory control and working memory) and psychological (e.g., motivation) factors linking PA with PTSD and stress symptoms. </p><p dir="ltr">A longitudinal lab-based study was conducted in Phase 1, which used trauma analogue techniques to induce participants’ responses to traumatic stimuli in a non-clinical sample. The aim of this first study was to examine whether cognitive interference (i.e., inhibitory control and working memory/sustained attention tasks) impacts trauma memory processing and subsequent intrusive memories (Chapter 2), and whether this association is moderated by PA (Chapter 3). Results showed that moderate PA levels and enhanced inhibitory control contributed to reduced intrusive memories and negative affect. Moderate PA levels and enhanced sustained attention contributed to reduced PTSD symptomatology. In contrast, high PA levels were associated with increased positive affect. </p><p dir="ltr">An intervention study was conducted in Phase 2 (Chapter 5), which examined how PA and acute exercise impact memory functioning (including autobiographical memory and future thinking) as well as emotional well-being in a sample of non-clinical adults. All participants were randomly assigned to cycling (i.e., acute exercise), stretching (i.e., active control), or video watching (i.e., non-active control) condition. Results showed that participants with higher PA levels reported increased autobiographical memory specificity than those with lower PA levels after a stretching session. Furthermore, participants reported increased positive affect, from either acute exercise alone or the combined effects of acute exercise and regular PA. </p><p dir="ltr">A cross-sectional online survey was conducted during the COVID-19 pandemic in Phase 3 (Chapter 7), investigating the effects of PA on mitigating stress symptoms resulting from the pandemic, and potential interactions between PA and psychological factors (specifically, motivation) in stress mitigation. Moreover, this study recruited participants from both Australia and China to further examine potential cultural influences. Australian participants demonstrated higher PA levels, but greater depression symptoms. In contrast, Chinese participants were less active and reported greater COVID-related stress and concerns. Moderation Analyses revealed the beneficial effects of PA and autonomous motivation on COVID-related health behaviours but also identified circumstances where they unexpectedly associated with negative well-being outcomes. </p><p dir="ltr">Chapter 8, as the final chapter, presents a general discussion of the key findings and implications of the outcomes across the three phases of research, concluding the positive effects of PA on emotional well-being, whilst highlighting the intricate interplays between PA, cognitive functioning, motivation, and stress mitigation.</p>