**Abstract**

There is considerable research indicating that exercise can be of significant benefit in reducing anxiety and depression. There are far fewer investigations of the role of exercise in reducing posttraumatic stress disorder (PTSD). This chapter reviews empirical research on the impact of exercise, particularly aerobic exercise, in reducing PTSD and negative emotional states. A variety of models are reviewed to possibly explain why exercise is so beneficial. Those who suffer from PTSD are notoriously treatment avoidant. Exercise is presented as an effective intervention for PTSD, anxiety, and depression and because it does not produce the level of avoidance that traditional psychotherapies do, it becomes a valuable potential tool for treating PTSD.

**Keywords:** posttraumatic stress disorder, anxiety, depression, exercise
