Physical fitness and activity levels decline substantially as we reach middle age

Physical fitness and activity levels decline substantially as we reach middle age, resulting in increased weight gain and increased risk of heart disease.

Those are the findings of the largest, long-term study of physical fitness change, presented by the Kaiser Permanente Division of Research today at the American Heart Association's 47th Annual Conference on Cardiovascular Disease Epidemiology and Prevention in Orlando, Fla.

The study included a large number of participants from two groups for which virtually no information on long-term physical activity change was available -- women and African Americans. The study followed 2,289 men and women, ages 18 to 30, over a 20-year period at four research sites across the U.S., including the Kaiser Permanente Division of Research in Oakland, Calif.

Study participants, comprised of both Caucasians and African Americans, saw their physical fitness levels decline by an average 28 percent, their weight increase by an average 20 percent, and their self-reported physical activity drop by an average 18 percent over a 20 year-period (1985-86 to 2005-06).

"While aging is something we have no control over, most of us do have the ability to control how physically active we remain as we get older," said Stephen Sidney, MD, MPH, the study's principal investigator and Associate Director for Clinical Research at the Kaiser Permanente Division of Research. "This study shows the importance of staying physically active throughout our lives and how we can better influence our fitness levels, and consequently, better manage our weight."

Fitness level declines in study participants were inversely associated with weight gains, and directly associated with changes in physical activity scores. "We know that low physical fitness levels put people at greater risk of cardiovascular disease and related deaths," said Dr. Sidney. "Staying physically active is also a great way to stave off obesity."

In the past 30 years, the prevalence of obesity among adults ages 20 to 74 has increased from 15 percent to nearly 33 percent, according to the Centers for Disease Control and Prevention.

Cardiorespiratory fitness in study participants was assessed by the amount of time they could exercise on a treadmill test. Physical activity was based on a self-administered survey covering 13 types of activities over a one-year timeframe. The American Heart Association recommends that all adults strive to get at least 30 minutes of moderate physical activity each day.

These research findings come from the Coronary Artery Risk Development in Young Adults (CARDIA) Fitness Study, funded by a grant from the National Heart Lung and Blood Institute (NHBLI), in conjunction with the CARDIA study, a 20- year observational study also funded by the NHLBI and conducted at four research centers across the U.S.

The Kaiser Permanente Division of Research conducts, publishes, and disseminates epidemiologic and health services research to improve the health and medical care of Kaiser Permanente members and the society at large. It seeks to understand the determinants of illness and well being and to improve the quality and cost-effectiveness of health care. Currently, the center's 400-plus staff is working on more than 250 epidemiological and health services research projects.