Written by Thomas S. Altena, Ed.D.
Cholesterol is everywhere! We cannot miss the commercials while watching television, and see it in print media. Indeed, media attention highlights the importance of cholesterol management, but sometimes cholesterol information can be confusing. Here is a simplistic summary of cholesterol, with a focus on the effects of exercise for prevention of and treatment for unhealthy cholesterol levels. Part of the cholesterol media blitz comes from pharmaceutical companies offering ways to manage cholesterol – yet management through exercise is often not mentioned.
The “cholesterol” molecule we know is a combination of fat and protein that is found in the blood stream. Different combinations of protein and fat make the molecule either healthy or harmful. Total cholesterol (TC) is the sum of all forms of cholesterol in the blood, with healthy TC typically being below 200mg/dl. Although TC is important, it only indicates the amount, not the type, of cholesterol. “Bad” cholesterol is classified as low-density lipoprotein cholesterol (LDL-C) and is a small molecule rich in fat and low in protein. LDL-C is the primary cholesterol form that causes atherosclerosis and eventual artery blockage, resulting in heart disease over time. Healthy values for LDL-C are stated as being below 100mg/dl.
High-density lipoprotein cholesterol (HDL-C) is known as “good” cholesterol because it has abundant protein in its molecule. It helps transport LDL-C back to the liver, where LDLC is disassembled and eliminated from the body. Healthy HDL-C values are 35-60mg/dl. Pre-menopausal women naturally have higher HDL-C than their same-age male counterparts. This difference is caused by estrogen and improves resistance to coronary heart disease in females compared to males.
Cholesterol is manufactured by the liver and can be influenced by fat in the diet, which appears in the blood as triglycerides (TGs). TGs alone are a risk factor for cardiovascular disease. When TGs are high in the blood, HDL-C decreases and LDL-C increases, creating a cholesterol profile that promotes cardiovascular disease. The effect of high TGs can be measured in just a few hours after eating a single meal that has even moderate amounts of fat. TGs in the blood are eventually transported to the liver and converted to unhealthy cholesterols. Cholesterol plays a role in every cell of the body, creating cell shape and function, and is partly is responsible for making skin waterproof.
Statin drugs made by pharmaceutical companies improve cholesterol by lowering TC and LDL-C and increasing HDL-C, but these drugs are not without potential adverse side effects. The statin option should be considered only after diet, exercise, and weight-loss programs have been attempted. Exercise, along with dietary changes, must be the first option for cholesterol maintenance. In research studies, aerobic exercise has effectively decreased or maintained TC while decreasing LDL-C. Research has also reported an 8-percent decrease in TC and slightly increased HDL-C after just four weeks of moderate-intensity (75 percent of maximum heart rate) jogging. Cholesterol changes occurred in just 20 exercise sessions of 30 minutes each. This same study reported that LDL-C size changed, making it less prone to cause heart disease. Other research suggests that the greatest cholesterol improvements occur with inactive people who lose weight, indicating that weight management and weight loss are important for improving cholesterol.
Research also suggests that the type of exercise performed may be important for cholesterol changes. Although beneficial for other areas of health, such as preventing osteoporosis, resistance training does not affect cholesterol levels as much as aerobic exercise. Resistance training typically does not change TC levels, but slightly increases HDL-C. Resistance training could play an important role with weight management and body composition, especially when combined with aerobic exercise. HDL-C tends to respond positively to higher intensities of exercise more than low intensities. Furthermore, all forms of aerobic exercise have potential to create positive changes in cholesterols.
In conclusion, exercise positively affects cholesterol, but prescription statin drugs may still be necessary. The benefits of exercise reach far beyond cholesterol alone, leading to increased efficiency of the heart, lungs, circulatory system, and muscular system. It also increases bone mineral density and expends calories, crucial to weight loss. Statin drugs cannot claim these benefits. Furthermore, exercise promotes a sense of well-being and accomplishment, improves energy levels, prevents fatigue, and improves psychological health. Cholesterol tends to be overlooked until a physician highlights personal risk for cardiovascular disease. Preventing unhealthy cholesterol levels is easier at a younger age because most people college age and younger do not typically have cholesterol issues. The key to controlling cholesterol is abundant physical activity – at least 30 minutes five days per week – along with a diet low in saturated fat and high in fiber.
Cholesterol: Cholesterol is a soft substance found in the blood, used to produce cell membranes, hormones and assist in other bodily functions.
LDL: Known as “bad” cholesterol, LDL can build up on the side walls of the arteries, leading to narrowed arteries and increased risk of heart attack or stroke.
HDL: Known as “good” cholesterol, HDL is believed to carry cholesterol away from the heart and into the liver, where it is purged from the body.
Triglycerides: A form of fat made in the body, high triglycerides often correspond with high levels of cholesterol.
View the full summer 2008 issue of the ACSM Fit Society® Page online.