A significant U-shaped association between physical activity level and posttraumatic stress disorder in U.S. military Veterans: Results from the 2019–2020 National Health and Resilience in Veterans Study

Objective: The present study sought to extend previous research by examining associations between physical activity levels, PTSD, and PTSD symptom clusters in a large, independent, nationally representative sample of U.S. military veterans. Methods: Using data from the 2019–2020 National Health and Resilience in Veterans Study (NHRVS), we examined relations between a comprehensive self-report measure of physical activity that reflects public health guidelines and a self-report measure of DSM-5-defined PTSD and a 7-factor model of PTSD symptom dimensions. A total of 3,875 participants completed all study measures. Post-stratification weights were applied to all analyses (weighted n = 3,732). Results: Quadratic logistic regression revealed a significant (p <.05) U-shaped association between physical activity levels (insufficient, moderate, and active) and a positive PTSD screen. A moderate activity level was associated with the lowest likelihood of PTSD (3.8% adjusted probability) while an active level was associated with the highest likelihood of PTSD (7.8% adjusted probability). Multinomial logistic regression suggested that more severe posttraumatic intrusive symptoms, particularly nightmares, and anhedonic symptoms were associated with a significantly decreased probability of a moderate activity level (ps ≤.05, false discovery rate corrected). Conclusions: Findings suggest that a moderate physical activity level is associated with a lower likelihood of PTSD but that specific PTSD symptoms may be differentially associated with exercise behaviors. Candidate mechanisms and clinical implications of these findings are discussed.