The study of 417 men and women, conducted by researchers at Northwestern University Feinberg School of Medicine, indicates that those who walked for exercise three or more times per week had a significantly smaller average annual decline in walking distance and speed than those who walked one to two times per week.
The study was led by Mary McGrae McDermott, M.D., associate professor of medicine, division of general internal medicine, at the Feinberg School.
The researchers also found that only a small proportion of African-American study participants walked for exercise three or more times per week. Previous studies have shown that African-American patients with PAD have greater functional impairment than white patients. Additionally, the prevalence of PAD is higher in African-Americans than in white patients.
"Data from the study suggest that doctors should take steps to encourage African-American individuals to increase their frequency of walking exercise," McDermott said.
Approximately 20 percent of the elderly have PAD. Research has shown that PAD tends to worsen over time, but participation in regular physical rehabilitation programs that include supervised treadmill walking at least three times a week has been shown to improve walking performance and slow the progression of the disease.
However, many patients with PAD have difficulty attending a supervised exercise program because of cost or transportation problems.
Results of the Northwestern study suggest that unsupervised walking exercise, such as that performed at home, also slows progression of PAD.
The researchers tested participants' physical ability by measuring the distance they could walk in 6 minutes and by observing their ability to get up from a chair unassisted; how well they maintained balance in a standing position; and how fast they could walk over a short distance.
The researchers also asked participants how often they walked for exercise and how long each walking session lasted. Besides showing that self-directed walking for exercise at least three times a week slowed decline in ability to perform physical activities, the study found that participants with the worst PAD at the start of the study were the ones most likely to benefit from a regular self-directed walking program.
McDermott's collaborators on this study were from Northwestern University Feinberg School of Medicine; Evanston Northwestern Healthcare; the National Institute on Aging; and the University of California-San Diego.
The study was supported by grants from the National Heart, Lung, and Blood Institute (grant numbers R01-HL58099 and R01-HL64739) and by the National Center for Research Resources, National Institutes of Health (grant number RR-00048). Northwestern is conducting another clinical research study to determine whether regular exercise can improve leg and ankle functioning in participants with PAD. For information on the PAD study, call (312) 695-2394.