Physical activity to prevent or reverse disability in sedentary older adults.

The articles in this supplement 1–13 to the American Journal of Preventive Medicine focus on physical activity and disablement in older adults. Epidemiologic research shows that habitually active older adults have a substantially lower risk of functional limitations and disability. But most older adults are not habitually active. About three of four older adults do not meet the Centers for Disease Control and Prevention (CDC) recommendation to do a brisk walk or equivalent type of activity for at least 30 minutes on 5 days each week. Appropriately, then, the articles focus mainly on the effects of increasing physical activity in sedentary and insufficiently active older adults and on promoting physical activity in older adults. Let us first consider a few important themes that emerge from the articles as a group and then consider a few of the interesting questions raised by the articles. While more research is needed, the evidence thus far suggests that physical activity is a potent intervention to prevent and/or reverse functional limitations and disability in sedentary older adults. For the past 20 years, studies have reported that physical activity improves physiologic impairments such as muscle weakness and low cardiorespiratory fitness. Over the past decade, evidence has accumulated that physical activity improves function limitations. The effects of physical activity on disability are less clear. Given the large number of determinants of disability and that any single intervention, such as exercise, affects only a subset of them, randomized trials that are larger and longer than most existing studies of physical activity are needed to address this issue. Some have expressed concern that some studies report only modest effects of physical activity on the disablement process. The modest effects may reflect the relatively low dose of physical activity in most controlled trials, which typically test doses of physical activity that do not even meet the minimum amount recommended in guidelines (at least 30 minutes on at least 5 days a week). Intervention durations typically range only between 3 and 12 months. As noted by several authors, measurement methods still need improvement. We need research that helps us to understand how the dose of physical activity relates to its effects on functional limitations and disability. Older adults benefit from diversity in their physical activity. Certainly the health benefits of walking (and equivalent types of aerobic activity) are substantial. But the articles on strength training and balance training discuss important health effects of these types of activity as well. While the benefits of flexibility training are not as well documented, maintaining flexible joints and muscles is obviously desirable. We struggle to understand the risks of physical activity in older adults and how to minimize them. Our communication illustrates the struggle. Sudden death is a risk of a sedentary lifestyle, and sudden death is more common in sedentary adults. But our tendency is to speak of sudden death as a risk of exercise. The common advice to consult a physician prior to starting an exercise program suggests an image of physical activity as risky. Recommendations on minimizing risks of activity are well intentioned, but since we lack evidence of their effectiveness, we wonder whether we are creating barriers to activity rather than minimizing risks. A major research priority is to improve our understanding of risks of physical activity in older adults and to gather information about effectiveness of strategies to reduce risks. Our theoretical models posit that policies and the physical environment play a critical role in helping older adults adopt active lifestyles, but data addressing this issue are sparse. In the case of tobacco control, policy interventions such as taxation of cigarettes and bans on indoor smoking have played a key role in reducing tobacco use. Environmental and policy interventions to increase physical activity could have a comparably large impact, and research is urgently needed. Regular physical activity is appropriate for virtually all older adults, and it is never too late to adopt an active lifestyle. In particular, the article discussing exercise programs for residents of long-term care facilities illustrates this theme. While the articles discuss these and other themes, they also raise several interesting questions. First, do we tend to underestimate the challenge of helping older adults adopt active lifestyles? It sounds so easy—just From the Physical Activity and Health Branch, Centers for Disease Control and Prevention, Atlanta, Georgia Address correspondence and reprint requests to: David M. Buchner, MD, MPH, Chief, Physical Activity and Health Branch, Centers for Disease Control and Prevention, 4770 Buford Highway, MS K46, Atlanta GA 30341-3717. E-mail: zdg4@cdc.gov.