Researcher Describes Physiological Differences that Put Women at Risk
Women should try to get 30 minutes of moderate intensity activity -- such as walking the dog or gardening -- most days.
When Heidi Kluess began studying cardiovascular disease, she didn't think she would find much difference between women and men.
She was surprised.
Kluess, an assistant professor of kinesiology at the University of Arkansas, spoke about her research recently at the 2009 Arkansas Health Disparities Conference. She described how the ways in which men and women differ put women at greater risk for cardiovascular disease and contribute to a disparity between the outcomes experienced by each gender. Her research on how the sympathetic nervous system controls blood flow and blood pressure in women as they age is funded by a grant from the National Institute on Aging, which is a part of the National Institutes of Health.
"Basically, I'm trying to learn how to fix cardiac disease," she explained. "My field is exercise science but I'm a disease person. Physiology is really interesting to me, but if you can run a marathon, you don't need my help."
With assistance from undergraduate and graduate students in the College of Education and Health Professions, Kluess studies tension in blood vessels harvested from female rats, whose physiology is similar to that of humans.
"We are trying to determine the physiological differences that make women's sympathetic nervous systems behave differently than men's," she said. "This is a very important question because cardiovascular disease is the No. 1 killer of women. It kills more women than men, but most women will say they are most afraid of cancer."
Cardiovascular disease manifests itself as heart disease, hypertension, peripheral arterial disease or stroke.
"Women often ignore the symptoms of cardiovascular disease," Kluess said, and that lowers their chance of recovery. "Their symptoms are sometimes different from those men suffer, such as stomach pain, and it may go away, leaving them thinking it's nothing to worry about. People think the symptoms will be very dramatic but they can be subtle. Women need to be sensitive to the warning signs and get help."
Warning signs for women include pain in the left arm, chest or jaw, shortness of breath, sweating and nausea.
Cardiovascular disease occurs anywhere in the body, causing damage to artery walls, which then form ridges of scarring that catch particles in the blood flow, Kluess explained. The body responds by sending white blood cells to the area to fight what is perceived as an infection and instead creating a "fatty mess" that closes the artery.
Some medical procedures to test for cardiovascular disease, such as angiography, are not as effective for women as for men, she said, and even surgical instruments may be too large for a woman's smaller physiology, slowing their recovery after surgery. More drug trials have used men rather than women, Kluess said.
After menopause, women lose the protection against high blood pressure that is afforded by hormones, which means more women over 65 suffer from hypertension than men in the same age group. Women experience more vasoconstriction, meaning the artery's ability to dilate is impaired.
Exercise, a healthy diet, not smoking and maintaining a healthy weight are the best preventive measures against cardiovascular disease, Kluess said. Women should try to get 30 minutes of moderate intensity activity most days, and the activity can be done in segments as short as 10 minutes. Exercise has been proven to lower blood pressure for up to 24 hours after it's completed.
"Where exercise scientists fail the most is getting people to be that active," she said. "Genetics determines 50 percent of your risk for cardiovascular disease, but you have control over the over 50 percent. Exercise will delay the onset and reduce symptoms."
There is some good news on the research front, Kluess reported. When awarding funding, the National Institutes of Health now requires scientific investigators to include women in clinical trials.
"Researchers tend to want homogeneous groups because diversity adds variables to their research, but now they must justify to the NIH if they want to exclude groups," she said. "That's a very important step the NIH has taken and it will help keep women healthy in the future."
Heidi Stambuck, director of communications
College of Education and Health Professions