ABSTRACT
The aim of this introductory chapter is to outline the raison d'être of this handbook. This is established by a sequence of arguments substantiating the following points. First, mental health problems are very prevalent in the industrialized world, are of exceptional societal importance, and exact a high cost both in terms of quality of life and in terms of economic impact. Second, a high percentage of individuals suffering from mental health problems do not seek help, and of those who do, many exhibit poor compliance with treatment regimens. Most likely, these phenomena are due to concerns related to the high cost of diagnosis and treatment, questions about the effectiveness of common treatments, and an unwillingness to risk or cope with adverse side-effects. Third, a growing corpus of evidence suggests that physical activity can be an inexpensive, safe, and, most importantly, effective lifestyle intervention that could be used to both prevent and treat a wide range of mental health problems and to improve overall quality of life. However, the effectiveness of physical activity as a mental health intervention is not universally acknowledged. For various reasons, many researchers and practitioners in medicine, psychology, and public health remain either uninformed or unconvinced about the potential of physical activity to promote mental health. Some of these reasons may stem from dualistic and disciplinary rifts and others from legitimate concerns about the methodological rigor of the extant studies. Distinguishing between these, and arriving at an accurate appraisal of the evidence, is becoming increasingly difficult.
