BOOKS & ELECTRONIC MEDIA

Perspectives on health and exercise

Tim Armstrong

STEPS Project Manager, Noncommunicable Diseases and Mental Health, Surveillance, World Health Organization, 1211 Geneva 27, Switzerland (email: armstrongt@who.int)

Editors: Jim Mckenna & Chris Riddoch
Publisher: Basingstoke: Palgrave Macmillan; 2003

This 300-page multi-authoured publication examines the relationship between physical activity and health. Broadly, it covers in valuable detail the science of physical activity, its effects on health, and the biological mechanisms related to those effects.

Of particular interest is the chapter by Carless & Faulkner on how mental health is affected by physical activity. For coronary heart disease, stroke, colon cancer, breast cancer, and diabetes the evidence is well established and unequivocal, but for mental health questions remain. The authors provide an excellent and comprehensive review of the research in this field. The evidence they cite clearly shows that participation in physical activity reduces the severity of mental illnesses, depression and anxiety. However, it is their treatment of how it relates to aspects of mental health such as self-esteem, autonomy and self-image that are the most enlightening. Few good studies exist in this area, but these authors have brought them together illuminatingly here. Some writers on this subject extol the benefits of physical activity without the supporting evidence, but Carless & Faulkner recommend a more open-minded and science-based view until more specific studies have been undertaken.

In the chapter about health outcomes, the review of the literature is not as comprehensive or up to date as might have been expected. It is certainly adequate, but more recent studies and large meta-analyses have been done in this area and were not included here. For example, the relative risk estimates provided for the impact of physical inactivity on coronary heart disease are based on a meta-analysis done in 1992. More recent work was not included. The relative risk estimates from the earlier studies probably overstate the benefits of physical activity by combining and confusing physical fitness and physical activity studies. Physical fitness and physical activity may have different relationships with health. A new meta-analysis undertaken by this reviewer, to be published later this year as part of the WHO Comparative Risk Assessment study, will show that for coronary heart disease the impact of 30 minutes of moderate physical activity a day, although substantial, may not be as great as was previously thought. Although it overlooks more recent data, the chapter still provides a good introduction to the premise that "participation in physical activity improves physical and mental health".

Overall, the authors make a welcome contribution to the growing literature on physical activity and health. Their work is well organized, referenced and presented, with a box at the start of each chapter indicating the topics covered and giving a concise summary.