People with high cholesterol have long assumed that in order to bring their levels within normal range, they need to shed a few pounds. But a recent study by Medical Center researchers suggests exercise alone--independent of weight loss--may have beneficial effects for those struggling with cholesterol problems.
The study, published in the New England Journal of Medicine, found that people who exercise regularly show improvement in the number and size of their high-density lipoproteins, or "good cholesterol." Members of the control group, who remained sedentary, experienced a decrease in the size and quantity of HDL and a corresponding increase in low-density lipoproteins, or "bad cholesterol."
The middle-aged, overweight subjects were separated into four groups and monitored for eight months. The three exercising groups, varying in intensity and amount, walked 12 miles per week, jogged 12 miles per week or jogged 20 miles per week. Members of a control group were allowed to do whatever they were doing before they entered the study. Additionally, those on the exercise regimen were urged to maintain their original body weight.
Cholesterol levels as a whole did not change for any of the exercising groups. Researchers, however, determined that the groups showed improvements in their lipoprotein profiles, meaning an increase in HDL and a decrease in LDL. Furthermore, the most pronounced benefits were discovered in the group that jogged for 20 miles per week.
"We have always known that exercise is beneficial to overall health and wellness, and essential for lowering cholesterol in specific," Jean Hanson, assistant director of student health, wrote in an e-mail. "Our health promotion efforts will continue to promote a balanced diet and appropriate exercise--but this new study gives us more reasons for saying so."
The control group did not show any signs of beneficial cholesterol or lipoprotein changes. Additionally, they gained an average of two pounds within an eight-month period.
"They gained a lot of weight in a very short period of time," said Cris Slentz, lead author of the study and research scientist in the department of medicine.
The results imply that the type of lipoproteins rather than total cholesterol levels are better indicators of health improvements and risks. "When you go to the doctor [to get your cholesterol checked], what is important to know is that the cholesterol level is misleading," Slentz said. "The public needs to know about it and its not-so-usefulness."
Slentz also said that when exercising, it is not only the intensity, but also the length of exercise that contributes to the best improvements in health. Above all, he stressed the importance of not being sedentary.
"Inactivity is dangerous," Slentz said. "You need to exercise six to eight miles [per week] to keep things they way they are, 10 to 12 miles will let you hang in there with some long-term improvement, and more than that if you want to see results quicker."
Krishaji Kulkarni, who works for a Birmingham, Ala., company called Atherotech, Inc., that provided lipoprotein measurements to the project, agreed that some amount of moderate exercise is important for good health.
"The research clearly shows that we need to do more than just a little walking to improve one's health and to see the real effects [of exercising] at the physiological level," Kulkarni said.
Both the amount and the intensity of exercise were compared to changes in overall cholesterol levels and the ratio of "good" and "bad" cholesterol.
The findings from this research are part of a larger study to be published later. Researchers were so impressed with these results that they felt compelled to publish the research before the rest of the study was completed.
"The results of the published article were based on 84 subjects. By the end of the study, there will be 240 subjects," Slentz said. "But even with 84 [subjects], the differences [between the variable groups] were loud and clear."
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