Exercise To Lower Cholesterol
Cynthia Dennison Haines, MD
You may have heard that exercise is one of the best ways to lower your cholesterol. But how does it work? And what type of exercise is most effective?
The Exercise-Cholesterol Link
Researchers aren't entirely sure how exercise lowers cholesterol, but they are beginning to have a clearer idea. "Lots of people, even lots of doctors, assume that exercise lowers cholesterol," says Amit Khera, MD, director of the University of Texas, Southwestern, Medical Center's Program in Preventive Cardiology. "But until recently, most of us weren't sure just what the connection was."
One way exercise can help lower cholesterol is by helping you lose -- or maintain -- weight. Being overweight tends to increase the amount of low-density lipoprotein (LDL) in your blood, the kind of lipoprotein that's been linked to heart disease.
Part of the confusion about the effect of exercise on cholesterol stems from the fact that most early cholesterol studies focused on both exercise and dietary changes, making it hard to tease out which of these factors was actually making the difference. But recent studies have more carefully examined the effect of exercise alone, making it easier to evaluate the relationship between exercise and cholesterol.
Researchers now believe there are several mechanisms involved. First, exercise stimulates enzymes that help move LDL from the blood (and blood-vessel walls) to the liver. From there, the cholesterol is converted into bile (for digestion) or excreted. So the more you exercise, the more LDL your body expels.
Second, exercise increases the size of the protein particles that carry cholesterol through the blood. (The combination of protein particles and cholesterol are called "lipoproteins;" it's the LDLs that have been linked to heart disease). Some of those particles are small and dense; some are big and fluffy. "The small, dense particles are more dangerous than the big, fluffy ones because the smaller ones can squeeze into the [linings of the heart and blood vessels] and set up shop there," says Khera. "But now it appears that exercise increases the size of the protein particles that carry both good and bad lipoproteins."