Even modest exercise may have cholesterol benefits

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Even modest exercise may have cholesterol benefits

Thursday, November 7, 2002 Posted: 12:32 PM EST (1732 GMT)

BOSTON (AP) -- Need another reason to exercise? Scientists have

discovered it makes cholesterol less dangerous.

A new study found that even modest exercise changes the size and density

of cholesterol-carrying proteins so they do less damage. And the

benefits occur even if people's total amount of cholesterol and their

weight stay the same.

Staying active has many health benefits, but improving cholesterol is

not usually considered one of them. People who exercise often lose

weight, and while that can improve their cholesterol levels, exercise by

itself was thought to have little or no effect.

Workouts fail to lower LDL, the dangerous form of cholesterol, and only

rigorous exercise can nudge up HDL, the good form that protects against

heart attacks.

But the study, by Dr. E. Kraus of Duke University, found a new

way that exercise can affect cholesterol -- by altering the number and

size of the particles that carry cholesterol through the bloodstream.

" People in the exercise field have always wondered why it doesn't affect

total cholesterol and LDL, " Kraus said. " We always knew low levels of

exercise are helpful. This helps solve that paradox. "

His work, published in Thursday's issue of the New England Journal of

Medicine, is the latest chapter in an evolving view of cholesterol's

effects. A generation ago, doctors worried only about the total amount

of cholesterol. Later, the importance of the main subtypes, especially

HDL, became apparent. Now experts are turning their attention to the

physical structure of cholesterol in the bloodstream.

With cholesterol, bigger is better

Cholesterol is an essential fat, or lipid. It circulates through the

body by attaching to protein particles. Cholesterol appears more likely

to clog the arteries when it is carried by small, dense protein

particles than when it is moved by relatively large, fluffy ones.

The latest study finds that people who exercise develop these bigger

particles, even if their total amount of cholesterol stays the same.

" Using this analysis shows clearly that exercise has beneficial effects

that are not revealed by standard tests, " said Dr. M. Krauss of

the Lawrence Berkeley National Laboratory, who studies the protein

particles.

The study, conducted at Duke and East Carolina University, involved 111

sedentary, overweight men and women. They were randomly assigned to

three exercise groups: the equivalent of walking 12 miles a week,

jogging 12 miles a week or jogging 20 miles a week. All were instructed

to eat enough to keep their weight constant.

They found that the cholesterol effects of walking and jogging 12 miles

were the same, while jogging 20 miles resulted in more pronounced

changes.

Measuring protein particle size is sometimes done in large medical

centers, but it is not part of standard physicals. Kraus said he expects

the tests, which cost two or three times more than standard cholesterol

tests, to become more widely used.

Dr. Joann Manson, head of preventive medicine at Harvard's Brigham and

Women's Hospital, noted that exercise has already been found to have

many other benefits for the heart, including improvements in blood

pressure, blood sugar, clotting and inflammation.

Studies show that briskly walking 30 minutes a day can lower the risk of

heart disease by 30 percent to 40 percent.

" Lipids are not the full story, " Manson said.