Exercise Improves Insulin Sensitivity in Polycystic Ovary Syndrome
DURHAM, N.C. - Duke University Medical Center researchers
have shown that moderate exercise – without accompanying weight
loss – can improve insulin sensitivity in women with polycystic
ovary syndrome, a group with a high risk of developing type 2
Polycystic ovary syndrome affects between six and 10 percent
of women of child-bearing age in the U.S. -- more than four
million people. Women with PCOS often have chronic weight
problems and carry the excess pounds in their abdomens, giving
them an "apple" figure. While medical treatment is important
for PCOS, women can also reduce their risk of developing
diabetes and heart disease by following a sensible diet and
exercise program, said Ann J. Brown, M.D., an assistant
professor of endocrinology at Duke University Medical
However, some women with PCOS have difficulty losing weight,
said Brown, lead author of the study. "Weight is a huge problem
for many of these women. We found that women can improve their
insulin resistance just with moderate activity.
"Even if you exercise and don't lose weight, you are still
reaping very important health benefits." Brown said.
The results were presented June 3, 2005, at the annual
meeting of the Androgen Excess
Society in San Diego, Calif. The research was supported by
the National Heart, Lung, and Blood Institute of the National
Institutes of Health.
The Duke researchers examined how exercise influenced the
way the body metabolized carbohydrates such as glucose in women
with PCOS who had not yet developed diabetes, but were at high
risk because they had insulin resistance.
"Anything that improves insulin sensitivity and decreases
insulin resistance is going to help prevent diabetes in the
long run," Brown said.
Insulin, a hormone secreted by the pancreas after a person
eats, is responsible for the regulation of glucose levels in
the blood. Over time, excessive amounts of insulin can lead to
complications associated with diabetes and heart disease. In
insulin resistance, the body's cells become less sensitive to
the effects of insulin, leading the pancreas to overcompensate
and produce even more insulin.
For the Duke study, nineteen sedentary women with PCOS were
assigned randomly to either a control group that continued
their sedentary lifestyle or a monitored exercise group. The
women were between ages 22 and 41 years and were insulin
resistant. The study group included ethnic minorities.
The exercise program was moderate in intensity, the
equivalent of walking briskly for one hour four days per week.
The women could talk easily while walking, Brown said.
Participants were not allowed to change their diet or lose
weight during the study, thereby enabling the researchers to
focus solely on the role of exercise in insulin resistance.
There was a small but significant improvement in insulin
resistance in the moderate exercise group. The group's insulin
resistance improved by up to 25 percent, with the amount of
improvement depending on the type of test used to measure
Because PCOS is an under-recognized condition, Brown
encourages women who suspect they are experiencing PCOS
symptoms to make an appointment with a health professional.
Early treatment can help prevent PCOS complications such as
diabetes, heart disease, infertility and endometrial
The most common PCOS symptoms are irregular menstrual
cycles, usually with fewer than 8 periods a year, acne and
excess facial and body hair. The syndrome is caused by a
hormonal imbalance -- too much androgen, or male hormone.
Brown's collaborators at Duke included Lori Aiken, Tracy
Setji, Linda Sanders, William Kraus and Laura Svetkey.