Sedentary behavior is a common but preventable cause of death, and an inverse linear relationship exists between all-cause mortality and volume of physical activity. Further, regular physical activity decreases the risk of type 2 diabetes, osteoporosis, obesity, cardiovascular disease, breast cancer, depression, colon cancer, and falls in older adults. Because of these numerous health benefits, various public health guidelines have been published on the recommended volume and intensity of physical activity. Therefore, the American Heart Association (AHA) has released a summary statement on physical activity interventions, which appears in the December 12, 2006, issue of Circulation.

The AHA's aim was to provide an overview of the population-wide impact of physical activity interventions. Along with the U.S. Surgeon General, the Centers for Disease Control and Prevention, and the American College of Sports Medicine, the AHA recommends at least 30 minutes a day of at least moderate-intensity physical activity on most, and preferably all, days of the week. However, despite the known benefits of physical activity, only 32 percent of adults and 66 percent of children and adolescents actively pursue leisure-time physical activity. It is imperative that interventions be designed to promote the adoption and maintenance of active lifestyles in large numbers of the population.

In older adults, behaviorally oriented approaches have shown short-term effectiveness, but long-term maintenance is not as strong. However, even brief interventions (three to 10 minutes) in health care settings have been shown to increase physical activity in patients over a short-term follow-up. Written prescriptions as well as verbal advice may also enhance the effectiveness of interventions. However, interventions that include behavioral strategies (e.g., goal setting, self-monitoring, feedback, problem solving) and supervised exercise are more effective than advice alone.

Adults spend most of their time at work, so the workplace has been examined as a setting for physical activity interventions. Although the evidence supporting workplace interventions is mixed, stronger evidence suggests that individually tailored behavior-change programs sent through e-mail or the Internet are effective. Incentives for positive behavior that do not undermine work productivity also may be considered.

Interventions delivered through the television, the telephone, the Internet, or in print have produced shortterm behavioral change among adults, and they may be effective in the longer term. Creating new opportunities for physical activity for recreational and transportation purposes (e.g., improving sidewalks, creating bike trails) may also prove to be valuable.

Research on physical activity interventions has grown, but employing these transdisciplinary efforts will be important for promoting physical activity among children and adults. The AHA notes that, to be successful, these efforts must be collaborative in theory development, hypothesis generation, study design, implementation, and analysis.