1. INTRODUCTION
Mental health lies on a continuum from having no symptoms and being fully functioning to having a
severe mental disorder. Mental disorders are not categorically distinct, but rather label the part of the
continuum where symptoms are longer lasting and cause disability. They are characterized by
problems in thinking, emotional state, and behavior. Mental disorders are common in Australia.
Recent studies show that the 12-month prevalence in adults was 14.4% for anxiety disorders, 6.2%
for affective disorders (such as depression) and 5.1% for substance use disorders (37). In addition,
the 12-month treated prevalence rate of psychotic disorders such as schizophrenia is 0.45% (26).
The population impact of mental disorders is principally on disability rather than on mortality. In
Australia, mental disorders are the third largest source of disease burden after cancers and
cardiovascular diseases, but the largest source of disability burden (4). This disability burden arises in
part because mental disorders often begin early in life and have a relapsing course. For anxiety and
affective disorders, the major treatment options are psychological therapy and antidepressant
medication, with the latter being appropriate for more severe cases (9). For psychotic disorders,
antipsychotic medication is a key component of treatment, but needs to be accompanied by
psychosocial intervention and practical support (33). The present review looks at the evidence for
exercise as a treatment option, in particular for depression, anxiety, and psychotic disorders.
There is a strong relationship between physical activity and mental health. Cross-sectional studies
show that regular physical activity is associated with better mental health and emotional well-being
(11) and lower rates of mental disorders (12). Longitudinal studies also show an association between
physical activity and reduced risk of developing a mental disorder (41). For example, a populationbased
study of 7076 Dutch adults found that engaging in physical exercise reduced the risk of
developing a mood or anxiety disorder over the 3-yr follow-up period, even when controlling for
sociodemographic characteristics and physical illnesses (41).
However, the relationship between physical activity and mental health is likely to be complex and
bidirectional. Physical inactivity may be the cause and/or the consequence of poor mental health, and
there may be common factors (such as overlapping genetic vulnerabilities) that predict both (6).
Consistent with the relationship between physical activity and mental health is that individuals with a
mental disorder are at higher risk of chronic physical conditions such as heart disease, diabetes,
arthritis, and asthma (40,45).