Shortly after World War II, health researchers began to investigate the high rates of coronary heart disease in the United Kingdom. Jerry Morris, a scientist in London, noted a striking difference in rates of myocardial infarction between drivers and conductors of double-decker buses. The conductors ascended and descended several hundred steps per day, and were about one half as likely as sedentary drivers to have sudden death from heart disease.¹ These findings are an important example of the effect of behavior on health: regular physical activity reduces the risk of chronic disease and premature death.²

However, the scientific consensus that regular physical activity provides major health benefits was not firmly established until the publication of the surgeon general's 1996 report Physical Activity and Health.³ Shortly before the publication of this report, the Centers for Disease Control and Prevention (CDC) and the American College of Sports Medicine (ACSM) issued public health guidelines on physical activity.⁴ The guidelines recommended that adults get at least 30 minutes of moderate-intensity activity on most, but preferably all, days of the week. Since then, scientific evidence on the health benefits of physical activity has continued to accumulate. In 2007, the U.S. Department of Health and Human Services (HHS) convened an expert committee to provide an updated review of the evidence.² Based on this review, the HHS released the 2008 Physical Activity Guidelines for Americans.⁵

In this issue of American Family Physician, Drs. Elsawy and Higgins summarize physical activity recommendations for older adults, mainly drawing from the HHS guidelines.⁶ The guidelines reflect that a medium amount of physical activity, around 150 minutes of moderate-intensity activity per week, provides major preventive health benefits in older adults. Physical activity also provides therapeutic benefits in persons with common chronic diseases, including cardiovascular disease, diabetes mellitus, osteoarthritis, obesity, osteoporosis, and depressive illness.⁷ The evidence is clear—regular physical activity is essential for healthy aging and provides substantial benefits to older adults, including those with chronic disease and a low fitness level.

Unfortunately, many Americans participate in low levels of physical activity, and little progress has been made in increasing these levels. An analysis of data from the National Health and Nutrition Examination Survey showed that when physical activity levels were assessed objectively using accelerometers, only 5 percent of adults met the minimum level of physical activity recommended in the CDC/ACSM guidelines.⁸ We clearly need to increase our commitment to promoting physical activity in all age groups, including older adults.

Primary care physicians should advise all older adults about the importance of physical activity, as well as appropriate types and amounts of physical activity. The ACSM and American Medical Association recently launched Exercise is Medicine (http://www.exerciseis medicine.org), an initiative that calls on physicians to assess and review every patient's physical activity program at every visit. For busy physicians to do this efficiently, support from clinical management systems and community resources is needed. In New Zealand, for example, the “green prescription” protocol links primary care physicians with community agencies that do most of the counseling and supervision of patients who wish to increase physical activity. This approach has been effective and has increased physical activity by an average of about 35 minutes per week per patient referred.⁹

It is crucial that primary care physicians participate in community partnerships that address barriers to physical activity. The U.S. Task Force on Community Preventive Services has identified eight evidence-based, community-level interventions that address environmental and policy determinants of physical activity.^10,11 For example, providing good access to facilities that provide opportunities for physical activity, such as parks and multiuse trails, leads to higher levels of activity in a community. The way streets are designed also affects physical activity levels in a community. Persons have higher levels of activity when they live in areas with well-lit streets, safe street crossings, traffic flow features such as traffic circles and speed bumps, and other characteristics that promote walking and biking. Addressing issues, such as access to parks and urban design, requires a community partnership among sectors, including parks and recreation, law enforcement, urban planning, transportation, education, architecture, public health, and medical care.

By implementing an evidence-based approach to promoting physical activity, we have an opportunity to improve the health of the public—particularly the older population. As a society, we need to increase our commitment to promoting physical activity. To be successful, we need continued leadership and involvement from primary care physicians.