Exercise Tie Defined in Control of Cholesterol

If you depend on a walking program to keep your cholesterol levels healthy, keep walking. Unless you’re making tracks for at least 2 1/2 hours a week, you’re probably not walking enough.

That’s the finding of a new study that examined the exercise walking habits of more than 3,600 adults and measured their blood cholesterol.

“People who walked “2 1/2 hours or more per week were half as likely to have elevated cholesterol than those who walked less,” said Larry A. Tucker, associate professor of physical education and director of health promotion at Brigham Young University in Provo, Utah. The study appears in this month’s American Journal of Public Health.

Adults in the study were divided into four groups: non-exercisers, low duration exercisers (30 minutes to two hours of weekly exercise walking), moderate duration exercisers (2 1/2 to four hours) and high duration exercisers (4 1/2 hours or more). For each exerciser, Tucker measured the ratio of total cholesterol to high density lipoproteins (HDL), the so-called good cholesterol that is thought to protect against heart disease. A ratio of 5 or greater was used to signify high risk, according to current recommendations, Tucker said.

Those who exercised at moderate or high levels were “less than half as likely to have ratios of 5 and above,” said Tucker, who co-authored the study with Dr. Glenn M. Friedman of Health Advancement Services, a Tempe, Ariz., corporate wellness firm. They found no significant differences in the ratios between the moderate and high duration exercisers, “but that doesn’t necessarily mean you should aim for the minimum,” Tucker said.

Tucker acknowledges the limitations of the study, which was partially funded by Health Advancement Services and the Rockport Walking Institute. Exercisers self-reported their activity and didn’t record walking speed or mileage. Tucker cautions against a cause-and-effect conclusion and says more research is underway.

But the study deserves attention, said John Duncan, associate director of exercise physiology for the Institute for Aerobics Research in Dallas. He said it may help experts address an old question: How much exercise is needed for fitness versus how much is needed for health maintenance and risk reduction. “I think this study provides another piece to the health prescription puzzle,” Duncan said.

For now, Tucker tells exercisers: “It looks like 2 1/2 hours or more of walking per week is most beneficial (for cholesterol levels). Where the optimal level is, we don’t know yet.”