Physical activity appears to reduce the risk of heart disease in women.
The reduction may be due in part to higher levels of high density lipoprotein
(HDL) cholesterol. In women, high plasma levels of HDL-cholesterol appear
to help prevent heart attacks. Our objective was to determine how vigorous
exercise can improve HDL and other coronary heart disease risk factors.
This was done by comparing physician-supplied medical data to reported
distance ran per week in a national cross-sectional survey of 1,837 women
recreational
runners. All had completed a two-page questionnaire as part of their
participation in the National Runners' Health Study.
The graph at lower left shows that HDL cholesterol (the good cholesterol) increased
significantly with each 10 mile increment in running mileage up to 40
miles per week. HDL-cholesterol increased significantly in premenopausal
women not using oral contraceptives, in postmenopausal women not taking
estrogen replacement, and in postmenopausal women taking estrogen replacement.
In women using birth control pills the results were less clear.
Body mass index (BMI) is a measure of a person's weight compared to
their height. It is widely used in epidemiological studies when a direct
measurement of a person's fat is not available. It is calculated as
weight (in kilograms) divided by the square of a person's height (in
meters). A BMI of 25 or less is desirable, 25-30 is moderately overweight,
and 30 or more is considered severely overweight. The graph on the following page shows
that women who ran a greater weekly distance were leaner.
