Increases HDLs
There's a good reason why the American Heart Association suggests exercise as a means of reducing cholesterol. In the past, diet alone was used as a means of reducing overall cholesterol. However, in some cases, dieting can also reduce your HDLs, also known as high density lipoproteins. HDLs are responsible for sweeping the fat from your blood, and transporting low density lipoproteins to the liver for excretion. As such, they are considered "good cholesterol". In contrast, the LDLs or low density lipoproteins are considered "bad cholesterol" because they carry cholesterol to the arteries. Those on a low fat diet will benefit from regular aerobic exercise which prevent HDL levels from dropping. In fact, HDL levels can be raised without diet by performing a minimum 30 minutes of aerobic exercise at least six days a week.
Lowering Triglycerides
While many experts state that exercise increases high density lipoproteins, few explain how this happens. Authors Rod K. Dishman, Richard A. Washburn and Gregory Heath describe the process in their book titled "Physical Activity Epidemiology". Prolonged aerobic exercise involves an increased use of triglycerides as fuel. During the workout, an enzyme known as LPL, or lipoprotein lipase breaks down the triglycerides into fatty acids. This process causes the LDLs or low density lipoproteins to shrink, and lose part of their surface to the HDLs. The HDL level is therefore increased.
Excretion
In their paper titled "A Review of the Impact of Exercise on Cholesterol Levels", Chantal A. Vella, Len Kravitz, Ph.D., and Jeffrey M. Janot of the University of New Mexico explain how exercise helps lower cholesterol through excretion. Aerobic exercise stimulates enzymes that transport the LDL cholesterol to the liver, where it is converted into bile and eliminated through excretion.
Increase Transporter Size
The proteins that carry cholesterol through the bloodstream are called lipoproteins. Exercise increases the size of these transporters. The smaller LDL-carrying lipoproteins can easily sneak into the lining of your heart and clog your arteries. Clogged arteries may eventually lead to heart disease. Making the lipoproteins larger through exercise can protect your heart from damage.
Weight Loss
Overweight people tend to have high levels of LDL or bad cholesterol. When they lose weight through aerobic exercise, they are able to lower their LDL levels.
Decrease Hepatic Lipase
Hepatic lipase is an enzyme in the liver. It is responsible for the catabolism or breakdown of the HDL cholesterol. The authors of "Physical Activity Epidemiology" have speculated that regular aerobic exercise might decrease hepatic lipase activity. This in turn can limit the breakdown of HDL cholesterol, thereby leaving more in the bloodstream.
Smoking Cessation
Smoking has been linked to high LDL cholesterol levels. Since it's often difficult for smokers to perform full-length aerobic exercise sessions, beginning a workout program may motivate them to quit the smoking habit. In this case, exercise may have an indirect effect on lowering cholesterol.
