Last Updated: 2002-11-06 17:00:57 -0400 (Reuters Health)
By Amy Norton
NEW YORK (Reuters Health) - When it comes to lowering cholesterol, it seems the amount of exercise a person logs is more important than the intensity, researchers report.
Their study of previously sedentary, overweight adults found that more exercise was better than less, with high amounts of intense activity--the equivalent of jogging about 18 miles a week--showing the strongest effects on participants' cholesterol levels.
Fortunately, the study authors say, this doesn't mean people need to run miles each day to see a cholesterol dip. Participants who exercised at all came out of the study with better cholesterol profiles than those who remained inactive, lead author Dr. William E. Kraus pointed out in an interview with Reuters Health.
What the findings do mean, according to Kraus, is that, at least as far as cholesterol is concerned, it may be the amount of exercise that's really important. Among study participants who exercised relatively less, his team found no clear cholesterol differences between those who exercised intensely and those who engaged in moderate activity--although both groups had more healthful cholesterol levels than those who stayed sedentary.
What's more, active participants saw these cholesterol benefits while losing only a little weight. This shows that exercise can create heart-healthy changes "inside the body" even when the benefits are not yet evident on the outside, according to Kraus, a cardiologist at Duke University Medical Center in Durham, North Carolina.
"People should not get discouraged if they're not losing weight," he said, noting that factors like increased muscle may keep exercisers from seeing much of a difference on their bathroom scales right away.
Kraus and his colleagues report their findings in the November 7th issue of The New England Journal of Medicine.
Exercise has long been promoted for its cardiovascular benefits, one of which is thought to be more healthful cholesterol levels. But studies have yielded inconsistent findings on whether exercise, on its own, really does boost "good" HDL cholesterol and lower "bad" LDL cholesterol. One question has centered on the amount and intensity of exercise needed to affect cholesterol and other cardiovascular factors.
In the current study, 111 middle-aged adults with elevated cholesterol were randomly assigned to an inactive "control" group or one of three exercise groups. One group, the "high-amount/high-intensity" group, logged the calorie-burning equivalent of jogging 17 or 18 miles a week. The two lower-amount groups completed the equivalent of jogging (high-intensity) or walking (moderate-intensity) about 11 miles per week. All of the exercisers used machines such as treadmills and stationary bikes.
After about 8 months of regular exercise, the high-amount/high-intensity group showed increases in heart-friendly HDL cholesterol, as well as the greatest improvements in components of LDL cholesterol. The HDL boost was seen only in this group.
The implication, Kraus said, is that "any exercise is better than none, more is better than less, and inactivity is bad."
He also noted that lesser amounts of regular activity may bring cholesterol benefits like those seen with high amounts of intense exercise, but just may take longer to do so.
The fact that substantial weight loss was not required for the benefits in this study is also important, according to an editorial accompanying the report.
"The study...provides a ray of hope for those who find it easier to exercise than to lose weight," writes Dr. Alan R. Tall of Columbia University in New York.
Still, Kraus and his colleagues are looking at whether losing weight enhances the positive effects of exercise on cholesterol.
SOURCE: The New England Journal of Medicine 2002;347:1483-1492.