Decreased heart rate variability (HRV) is associated with posttraumatic stress disorder (PTSD) and depression symptoms, but PTSD's effects on the autonomic stress response and the potential influence of HRV biofeedback in stress relaxation training on improving PTSD symptoms are not well understood. The objective of this study was to examine the impact of a predeployment stress inoculation training (PRESTINT) protocol on physiologic measures of HRV in a large sample of the military population randomly assigned to experimental HRV biofeedback-assisted relaxation training versus a control condition. PRESTINT altered the parasympathetic regulation of cardiac activity, with experimental subjects exhibiting greater HRV, that is, less arousal, during a posttraining combat simulation designed to heighten arousal. Autonomic reactivity was also found to be related to PTSD and self-reported use of mental health services. Future PRESTINT training could be appropriate for efficiently teaching self-help skills to reduce the psychological harm following trauma exposure by increasing the capacity for parasympathetically modulated reactions to stress and providing a coping tool (i.e., relaxation method) for use following a stressful situation
