Am J Epidemiol 2004; 159:910-911.
Copyright © 2004 by the Johns
Hopkins Bloomberg School of Public Health
BOOK REVIEWS |
Physical Activity Epidemiology
1 Stanford University School of Medicine, Stanford, CA 94305
2 Harvard School of Public Health, Boston, MA 02115
By Rod K. Dishman, Gregory W. Heath, and Richard Washburn
ISBN 0-88011-605-6, Human Kinetics, Champaign, Illinois (Telephone: 800-747-4457, Fax: 217-351-1549, Website: http://www.humankinetics.com), 2004, 488 pp., $59 (hardcover)
Only in the past 50–60 years have the unique and fundamental contributions of epidemiology been recognized; epidemiology offers both a means to understand the causes of chronic diseases and procedures to prevent and control such diseases. Both prospective and retrospective longitudinal observations have been used successfully to accomplish these purposes. The most reliable of such observations have examined host and environmental characteristics of cohorts of special populations in relation to the development of specific chronic diseases. For example, many prospective cohort studies have shown a physically active way of life to lower the risk of developing cardiovascular—hypertensive—metabolic diseases.
From time immemorial to this day, physical activity (or physical exercise) and physiologic fitness have been heralded as preventing disease and extending longevity. Physical Activity Epidemiology describes this activity through important messages from the past to our modern civilization about basic requirements of exercise, diet, and other lifeways for good health. It also leads us to current recommendations of physical activity for health, as follows: 1) Aim for 30 minutes per day of moderate-intensity activity. 2) This activity can be accumulated in bouts of more than 10 minutes, most (and preferably all) days of the week. 3) For those of all ages who are willing to do more, and for whom no contraindications exist, greater duration or intensity of activity can further reduce chronic disease risk.
Physical activity to promote good health can be defined in terms of type, frequency, intensity, duration, and timing of energy expenditure from using large skeletal muscles. Physical activity is a process, generally measured in kilocalories expended from muscle use per week. In cohort studies, it is usually assessed in terms of distance walked, number of stairs climbed, and recreation or sports play. Other methods used by exercise scientists to quantitate exercise include classification of a sport (e.g., tennis or running) into light, moderate, and vigorous play by amount of participation. Often used is quantity of energy measured in METs (metabolic equivalents), and it may be expressed in MET-hours per day.
As we all know, epidemiology is the study, in human populations, of the frequencies, distributions, and dynamics of a disease or a physiologic condition. The purpose of epidemiology is to search for the causes of disease, or how it is spread, and to identify a system for surveillance of its occurrence. In addition, its purpose is to assist with identifying pathogenetic mechanisms and the means of deterring disease (intervening, if you will). Thus, epidemiology requires use of clinical knowledge, laboratory support, inductive reasoning, statistical methods, simple logic, explicit honesty, and common sense. The key procedures in using it to assess cause-and-effect relations are comparison and contrast, with special reliance on inductive (circumstantial) reasoning. Through measurement and contrast, the methods determine whether people who are more active or physiologically fit experience a lower incidence of disease than do people less active or fit. Where a positive relation thus is demonstrated, epidemiology seeks to verify by further evidence, to establish gradient dose responses, to eliminate confounding influences, to find collateral circumstances, to establish biologic mechanisms, or to develop optional hypotheses. Often, this amassed evidence, inferential though it may be, will support or negate a causative relation.
Physical Activity Epidemiology accomplishes its stated purpose, namely, by describing "why physical inactivity is a burden on public health and what can be done about it" (1, p. xvii). In four parts and 10 chapters, the book deals with history and measurement, categorical chronic diseases, personal and environmental characteristics, allied diseases, hazards and disabilities, intervention techniques, and exercise maintenance. Orderly, chronological, and cross referenced, the book makes for easy reading and denotation. Emphasis is placed on coronary heart disease, stroke, hypertension, type II diabetes, osteoporosis, cancer, mental illness, and obesity—all in some way influenced by physical activity or inactivity. Additional sections deal with the immune system and lipoprotein profiles and with physical activity hazards and disabilities. The final chapter on adopting and maintaining a physically active lifestyle is especially insightful.
The authors are imaginative in the design and compilation of their book, painstaking in their assemblage of data, precise in the description of their findings, and logical in their inferential reasoning.
To give this review a reverse twist, however, we might ask whether there really is need for another book on physical activity as it is related to epidemiology. The resounding answer should certainly be yes, for a number of reasons. Despite its rather incongruous title, Physical Activity Epidemiology (grammatically, nouns do not modify nouns) presents a well-organized, comprehensive story of predictive and prognostic characteristics of health and longevity resulting from a physically active and fit lifeway. The book extends and amplifies the current, foremost such text, namely, Physical Activity and Health: A Report of the Surgeon General (2). Other well-established books provide different perspectives on the same topic (3–10). Some of the latter extend more comprehensively such topics as diet, weight control, and obesity (11–13), which currently hold much interest in the quest to relate exercise and diet to health, disease, and longevity. Perhaps Physical Activity Epidemiology does not emphasize sufficiently the influence of interactions among physical activity, diet, and weight control for health during all ages, especially for children. The same could be said about the metabolic syndrome and about genetics and molecular biology. Missing, for example, are data on tai chi, an increasingly popular sport, and its value in promoting proper balance and in preventing falls and fractures. The choice of learned sayings to introduce each chapter is appropriate; however, the photographs definitely are unneeded and inappropriate. Furthermore, one might claim the book to be too repetitive, which can be excused by the book’s format.
In its 8'' x 11'' format, and more than 1'' thick, Physical Activity Epidemiology in hardcover form is no pocketbook. Yet, it is well illustrated with tables and figures and with sidebars that contain key messages and featured points. The authors have done a good job. Read the book and keep it handy for reference.
In sum, Physical Activity Epidemiology is a wide-ranging, absolutely current, and commonsense guide to health in terms of physical exercise, as viewed from population-based studies. From prelude to postlude, the book is comprehensive and detailed, yet it is pleasurable to read, to contemplate over, and to reread as a reference text. Well done.
REFERENCES
- Dishman RK, Heath GW, Washburn R. Physical activity epidemiology. Champaign, IL: Human Kinetics, 2004.
- US Department of Health and Human Services. Physical activity and health: a report of the Surgeon General. Atlanta, GA: US Department of Health and Human Services, Centers for Disease Control and Prevention, National Center for Chronic Disease Prevention and Health Promotion, 1996.
- Cooper KH. Aerobics. New York, NY: Evans and Co, 1968.
- Morris JN. Uses of epidemiology. 3rd ed. Edinburgh, United Kingdom: Churchill Livingstone, 1975.
- Fixx JF. Jim Fixx’s second book of running. New York, NY: Random House, 1980.
- Eaton SB, Shostak M, Konner M. The Paleolithic prescription: a program of diet and exercise and a design for living. New York, NY: Harper and Row, 1988.
- Berryman JW. Out of many, one: a history of the American College of Sports Medicine. Champaign, IL: Human Kinetics, 1995.
- Paffenbarger RS Jr, Olsen E. LifeFit. Champaign, IL: Human Kinetics, 1996.
- Noakes T. Lore of running. 4th ed. Oxford, United Kingdom: Oxford University Press, 2001.
- Kolata G. Ultimate fitness: the quest for truth about exercise and health. New York, NY: Farrar, Straus and Giroux, 2003.
- Bennett WB, Gurin J. The dieter’s dilemma: eating less and weighing more. New York, NY: Basic Books, 1982.
- Willett WC. Eat, drink, and be healthy. New York, NY: Simon and Schuster, 2001.
- Brownell KD, Horgen TB. Food fight. New York, NY: Contemporary Books, 2004.
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