Prospectively assessed posttraumatic stress disorder and associated physical activity

Objectives

We examined the association of physical activity with prospectively assessed posttraumatic stress disorder (PTSD) symptoms in a military cohort.

Methods

Using baseline and follow-up questionnaire data from a large prospective study of U.S. service members, we applied multivariable logistic regression to examine the adjusted odds of new-onset and persistent PTSD symptoms associated with light/moderate physical activity, vigorous physical activity, and strength training at follow-up.

Results

Of the 38,883 participants, 89.4% reported engaging in at least 30 minutes of physical activity per week. At follow-up, those who reported proportionately less physical activity were more likely to screen positive for PTSD. Vigorous physical activity had the most consistent relationship with PTSD. Those who reported at least 20 minutes of vigorous physical activity twice weekly had significantly decreased odds for new-onset (odds ratio [OR] = 0.58, 95% confidence interval [CI] 0.49, 0.70) and persistent (OR=0.59, 95% CI 0.42, 0.83) PTSD symptoms.

Conclusions

Engagement in physical activity, especially vigorous activity, is significantly associated with decreased odds of PTSD symptoms among U.S. service members. While further longitudinal research is necessary, a physical activity component may be valuable to PTSD treatment and prevention programs.Recent military operations in Iraq and Afghanistan have been characterized by sustained ground combat, persistent risk, and multiple protracted deployments. Increased psychological symptom reporting has engendered heightened concern for the postdeployment mental health of service members and, in particular, the public health burden of posttraumatic stress disorder (PTSD).^1–4 A previous study using data from all U.S. service branches identified new-onset self-reported PTSD symptoms in 7.6%–8.7% of deployers who reported combat exposures, 1.4%–2.1% of deployers who did not report combat exposures, and 2.3%–3.0% of nondeployers.⁴PTSD is associated with poor physical health as well as negative health behaviors, such as tobacco use and problem alcohol drinking.^5–11 The extent to which behavioral correlates of PTSD mitigate or mediate PTSD symptoms and associated morbidities is currently under investigation.¹² While research has focused on adverse health behaviors, the relationship between positive health behaviors (e.g., physical activity) and PTSD has not been fully explored.Studies of depression and anxiety have pointed to the mental health benefits of physical activity, and researchers have postulated a number of mechanisms by which physical activity may modulate mood and the stress response.^13–19 While previous research indicates that physical activity may mitigate PTSD and related symptoms, other studies indicate that exercise habits of PTSD patients may be substandard.^20–23 In a retrospective study among Brazilians, physical activity levels decreased after the onset of PTSD.²⁴ These previous studies, however, were limited by small sample sizes, retrospective designs, and an inability to control for possible confounders.^20,22–25 The purpose of this study was to investigate new-onset, resolution, and persistence of PTSD symptoms in relation to type and quantity of physical activity in a large, population-based cohort of U.S. military service members.