Nearly 50 percent of Americans are not active enough for optimal health and disease prevention. This staggering statistic served as a launching point for public health advocate Barbara E. Ainsworth, Ph.D., MPH, FACSM, who delivered a President's Lecture at the 55th American College of Sports Medicine Annual Meeting in Indianapolis.

"Of the four modifiable risk factors for coronary heart disease, one is physical inactivity," said Ainsworth, emphasizing public health approaches to promoting physical activity. "Essentially, half of the U.S. population is throwing caution to the wind, and that's why physical inactivity has become a public health issue."

Ainsworth believes the answer to increasing physical activity is coordinated, integrated and funded steps targeted to the general public. Effective awareness among the diverse U.S. population must be culturally and socially relevant, reach across socio-economic levels, and touch all ages, she says.

At a 2006 ACSM Scientific Roundtable aimed at improving public health policy, a group of exercise science and health professionals called for a different health policy paradigm and new national efforts. Among the recommendations was a call for national guidelines for physical activity to be regularly developed, updated and promoted. Ainsworth noted that in March of this year, ACSM helped facilitate the launch of The Physical Activities Guidelines for Americans Act*, which would direct the Department of Health and Human Services (HHS) to prepare and promote physical activity guidelines for Americans every five years.

"We need a physical activity plan at the federal level," Ainsworth said. "We need to encourage programs aimed at creating an environment conducive to physical activity, and we need to encourage and support policies at the governmental and private sector levels that promote physical activity as well."

Among the environmental approaches, Ainsworth notes a need for more free or low-cost parks and recreational facilities, more sidewalks, and an increase in bike trails and lanes. On the policy side, she says more communities should adopt policies for increased physical education in schools, and modified housing policies to encourage people to live closer to work.

Ainsworth believes the U.S. has become a society fixated on making inactive behaviors convenient. As an example, she cites how escalators and elevators are prominently placed in buildings, but finding the staircase isn't always as easy. However, Ainsworth is quick to point out that the policies cannot be punitive; rather, they must be designed to encourage physical activity.

"Our greatest teacher in improving the physical activity of this nation is our experience with tobacco," she said. "Through high-quality research, coordinated mobilization, legislative changes and impacting policy, we have been able to slow down tobacco usage."

Beyond eliminating the risk of coronary heart disease, Ainsworth highlighted other quality of life benefits of physical activity such as increased productivity and improved mental health.

ACSM recommends that all healthy adults ages 18 to 65 years need moderate-intensity aerobic physical activity for at least 30 minutes on five days each week or vigorous-intensity aerobic physical activity for at least 20 minutes on three days each week.

The American College of Sports Medicine is the largest sports medicine and exercise science organization in the world. More than 20,000 international, national, and regional members are dedicated to advancing and integrating scientific research to provide educational and practical applications of exercise science and sports medicine.

*U.S. Senators Tom Harkin (D-IA) and Sam Brownback (R-KS), along with Representatives Mark Udall (D-CO) and Zach Wamp (R-TN) introduced legislation aimed at improving the health and wellness of Americans on March 12, 2008.

The conclusions outlined in this news release are those of the researchers only, and should not be construed as an official statement of the American College of Sports Medicine.

American College of Sports Medicine