Physical Fitness Influences Stress Reactions To Extreme Military Training

Abstract

Although several risk factors for posttraumatic stress disorder (PTSD) have been identified, researchers continue to search for novel predictors of this disorder. PURPOSE: In the current study, we prospectively examined whether physical fitness influences the impact of stressful events (a known predictor of PTSD) during military survival training in 31 men. We hypothesized that physical fitness would buffer stress symptoms and that the effect would be mediated via a fitness-associated attenuation in trait anxiety. METHODS: Participants reported their most recent Physical Readiness Test scores and completed a trait anxiety measure prior to survival training. Participants also completed the Impact of Events Scale (IES) 24 hours posttraining. RESULTS: Aerobic fitness was inversely associated with the total IES score (β = .015, p < .01, adjusted R2 = .19), independent of age, body mass index, years of military service, education, and Military Occupational Specialty. When adjusted for trait anxiety, this relationship was substantially attenuated and no longer significant (β = .009, p = .11). Trait anxiety was inversely associated with aerobic fitness (r = −.43, p < .05) and positively related to IES (r = .56, p < .001). CONCLUSIONS: These findings suggest that physical fitness may buffer stress symptoms secondary to extreme military stress, and its effects may be mediated via fitness-related attenuations in trait anxiety. This study was supported by the Office of Naval Research, Award No. N0001406WX20141.