Findings lend support to moderate exercise recommendations from CDC and NIH
CHICAGO - Increasing physical activity levels are associated with a substantial reduction in risk of total and ischemic stroke in women, according to an article in the June 14 issue of The Journal of the American Medical Association (JAMA).
Frank B. Hu, MD, PhD, from the Harvard School of Public Health, Boston, and colleagues studied a total of 72,488 female nurses from the Nursesí Health Study, whose ages ranged from 40 to 65 and who resided in 11 states across the U.S. These nurses, who did not have any diagnosed cardiovascular disease or cancer at baseline in 1986, also completed detailed physical activity questionnaires in 1986, 1988, and 1992.
During eight years of follow-up (to 1994), 407 new strokes occurred among the women. The authors found that after controlling for age, body mass index, history of hypertension, and other factors, increasing physical activity was strongly inversely associated with risk of total stroke. Walking was associated with reduced risk of total stroke. The researchers also found that a brisk or striding walking pace was associated with lower risk of total and ischemic stroke compared with average or casual pace walking.
"We observed comparable magnitudes of risk reduction with equivalent energy expenditures from walking and vigorous physical activity," the authors write.
According to background information in the study, current guidelines from the Centers for Disease Control and Prevention (CDC), and the National Institutes of Health (NIH), recommend that Americans should accumulate at least 30 minutes of moderate-intensity physical activity on most, preferably all days of the week. The authors add that the role of low- and moderate- intensity activities (such as walking), compared with vigorous exercise, in the prevention of cardiovascular disease remains controversial.
"Another important finding of our study is that sedentary women who became active in middle and later adulthood had lower stroke risk than their counterparts who remained sedentary. This implies a relatively prompt effect of physical activity -- older adults can enjoy the benefit of exercise even if they were sedentary for a long time," the researchers write.
The authors speculate that the protective effect of physical activity may be partly mediated through its effect on various risk factors for stroke.
"Physical activity lowers blood pressure and increases high-density lipoprotein cholesterol ['good' cholesterol] concentration," and the researchers also note that "physical activity facilitates weight loss and weight maintenance."
"Our findings lend further support to current guidelines from the CDC and NIH that promote regular moderate-intensity physical activity for prevention of chronic diseases," the authors conclude.
The researchers add that if walking is confirmed to provide the same benefits as more vigorous forms of physical activity, it will have important public health implications because walking is the most popular form of physical activity, especially among middle-aged and older women.
(Journal of the American Medical Association. 2000; 283: 2961-2967)
For more information about the Journal or to obtain a copy of the study, contact the American Medical Associationís Barry Cohn at 312-464-4579 or e-mail: Barry_Cohn@ama-assn.org .
Posted by the Center for the Advancement of Health http://www.cfah.org . For information about the Center, call Petrina Chong, pchong@cfah.org 202-387-2829.
Journal
JAMA