Just an hour's walk a week, even at only 3 or 4 miles an hour, can lower a woman's risk of heart disease, according to a new study.
"While there's clear evidence that more vigorous exercise is even more beneficial, we're saying that it is possible to see some gain in heart health without the pain," said I-Min Lee, who led the research team at Brigham and Women's Hospital and Harvard Medical School in Boston.
"Our results show that very modest physical activity can reduce the risk of heart disease in women by up to 45 percent over those who are completely sedentary," Lee said.
Heart researchers have known for more than a decade that physical activity contributes to heart health, but the studies have tended to look for the effects of exercise at the higher end of the scale - aerobics or jogging rather than just plain walking.
Lee said the new study, published Wednesday in a special issue of The Journal of the American Medical Association devoted to women's health issues, "looks at exercise closer to where most American women really are - little or no physical activity on a regular basis. Thirty percent say they do zero. But even getting out there and walking for an hour can make a difference and it's the most common activity that women do."
Lee and her colleagues used data collected from more than 39,000 healthy women aged 45 and older enrolled in the Women's Health Study between September 1992 and May 1995, with follow-up done until March 1999. The women are also taking part in a long-term study on the health benefits of aspirin and vitamin E in fighting heart disease and cancer.
The women reported the time they spent each week on recreational and daily physical activities, including walking and stair climbing. The authors computed the energy expended for all the activities each week and matched those levels against the heart disease experienced by the women.
There were 244 confirmed incidents of heart disease among the women, including heart attacks, deaths from heart disease, bypass surgery or angioplasty procedures.
Those with more vigorous activities had lower risk, but among regular walkers, the amount of time rather than the pace seemed to matter most.
"Walking doesn't have to be fast-paced to benefit," the researcher said. "Time spent walking was more important than walking pace."
The connection held even among women who were overweight, had increased cholesterol levels or were smokers, according to the study.
"In the '70s and '80s, most recommendations were for vigorous exercise, at least 20 minutes for three days a week. Now, the standard is for all adults to accumulate 30 minutes or more of moderate-intensity physical activity on most or all days of the week," Lee said.
"I think our study supports this recommendation. The bottom line is, doctors have to give their patient a goal they can meet. Walking an hour a week isn't out of reach for most women. Then, if they can hit that milestone, they can try to move ahead to two or three hours a week and beyond," Lee added.
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