It has long been speculated that there is a relationship between exercise and it effects on anxiety and depression. However, it is not until recently that research has shown that exercise is associated with positive changes in mood and reductions in anxiety and depression. According to the Mental Health Victoria, depression is characterised by prolonged feelings of sadness, dejection and hopelessness and will affect one in four women and one in six men at some point in their lives. In the United States, anxiety disorders and depression are the most common mental health disorders costing the public $45 billion a year (Berger, Pargman & Weinberg, 2002, pp. 398). Although people typically deal with these mood disturbances through psychological counseling, drug therapy, or both, more and more individuals are looking to exercise to promote their psychological well-being (Berger, Pargman & Weinberg, 2002, pp. 398). The effects of exercise can be classified as either acute or chronic. Acute meaning immediate, but not necessarily, temporary effects arising from a single bout of exercise, and chronic relating to the long-term effects of exercise focusing on changes over time (Berger, Pargman & Weinberg, 2002, pp. 398). The vast majority of research on the relationship between exercise and psychological well-being has used aerobic exercise and it was once believed that exercise needed to be of a sufficient duration and intensity to produce positive effects, however, more recent studies have indicated that high-intensity aerobic activity is not completely necessary to produce positive benefits, and that activities such as weight or strength training and other non-aerobic exercises can produce positive effects on psychological well-being (Berger, Pargman & Weinberg, 2002, pp. 399).
Studies of how exercise influences the reduction of anxiety have typically