Walking as Little as Hour a Week Good for Women's Hearts

From the WebMD Archives

March 23, 2001 -- (Orlando, Fla.) Take a hike, willya? Or a leisurely stroll. Or try the stairs instead of the elevator. Women who walk as little as about one hour per week have about half the risk of heart disease as women who never get off their, er, sofas, report Harvard University researchers in the Journal of the American Medical Association.

And if that's not enough to get you going, consider this: Overweight women who get some exercise still fare better when it comes to risk factors for heart disease than overweight women who are sedentary. That conclusion comes from a study presented at the annual scientific sessions of the American College of Cardiology here.

In other words, it may be possible to be fat and fit, at least where preventing heart disease is concerned, says C. Noel Bairery Merz, MD, and colleagues from Cedars-Sinai Medical Center in Los Angeles. She and her colleagues found that among overweight women undergoing evaluation for possible coronary heart disease, those who rarely or never performed strenuous activities were more likely to have signs of insulin resistance -- a risk factor for type 2 diabetes and heart problems related to it. In addition, inactive women also had much higher blood levels of triglycerides, a harmful form of fat, than the active women.

"We were interested in evaluating the role of obesity and physical activity, and prior data had suggested that obesity probably is not the true risk factor for heart disease, that it might just be a [sign] for physical inactivity," says Merz, director of preventive cardiology at Cedars-Sinai and associate professor of medicine at the University of California at Los Angeles.

They looked at nearly 700 overweight women whose doctors had ordered angiography, an imaging of the blood vessels supplying the heart, because of a suspicion of coronary artery disease. The women were defined as being overweight if they had a body mass index of 25 or greater, equivalent to being 20% or more above ideal body weight.

Only 14% of the women were considered to be physically active, meaning that during their daily activities -- working, housework, recreation, etc. -- they tended to do things more actively than others, such as taking stairs rather than the elevator.

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"When we looked at those 14% -- these are fat ladies but physically active -- they had much lower blockages of their coronary arteries, much lower fasting blood sugars, they had narrower waists, and they had much lower triglycerides, and when we lump those together, that's a bit of the insulin-resistance syndrome," Merz tells WebMD. "These overweight ladies are at risk for insulin resistance and diabetes, but if you're physically active, then the overweight part doesn't turn into insulin resistance."

You don't have to be overweight to see real benefits from even modest exercise, agrees I-Min Lee, MBBS, ScD, associate epidemiologist at Brigham and Women's Hospital and associate professor of medicine at Harvard Medical School in Boston. Lee is the author of the JAMA article.

"Our study found that walking at least an hour a week regardless of pace is associated with lower risk of heart disease, and this is a lesser level of physical activity than has been shown in previous studies," Lee tells WebMD. She says that it's only human nature to try to get away with as little as possible, including exercise. And when recommendations change as they have over the past few years -- from "No pain, no gain" (go all-out at least three times per week) to "train, don't strain" (exercise less strenuously but more frequently), people tend to get confused.

Interestingly enough, both approaches burn off about the same amount of calories, Lee says. "It's just offering people a choice: Do you want to do it vigorously over a short period of time, or do you want to do it moderately over a longer period of time. We really don't have a lot of information, especially in women, regarding the kinds of intensive activities that might be beneficial for them."

Lee and colleagues looked at data on nearly 40,000 women who took part in a nationwide health study, and looked for a relationship between exercise and recreational activities and coronary heart disease. In all, there were 244 cases of coronary heart disease, and after the researchers eliminated other possible causes of heart disease, they found that women who walked at even a leisurely 2 to 3 miles per hour still had about a 44% to 30% lower risk for heart disease than women who never get moving at all.

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"These data suggest that walking need not be fast-paced for benefit; time spent walking was more important than walking pace," Lee and colleagues write.

They also found that even light activities had heart benefits for women who were overweight, smoked, or had high cholesterol.

"If you do nothing, a little will help you. If you're already doing something, to get more benefit you need to do more," Lee tells WebMD. "One hour a week is actually less than what is currently recommended, and because of that, I feel that confirmation of these findings would be desirable, and my conservative interpretation of these data would be to say that they do support current recommendations for moderate-intensity for physical activity, half an hour a day most days of the week. I think what's really encouraging is that this study suggests that perhaps even doing lesser levels of activity may also be beneficial."

WebMD Health News Reviewed by Gary D. Vogin, MD
© 2001 WebMD, Inc. All rights reserved.

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