Introduction
Over the past twenty years, it has become evident that elevated levels of cholesterol and lipid components are risk factors for cardiovascular disease. Lipid molecules (especially the lipoproteins) are large molecules of fat (cholesterol and tyiglycerides) combined with proteins. Although fat in the body in general performs important functions, such as lining the walls of each cell, and the formation of certain hormones (like testosterone and estrogens), over abundence of these molecules creates its own set of problems.
Types of Lipids
Of the many classes of lipids, it is well established that there are two classes that affect general health, and are affected in turn by exercise. The first group consists of cholesterols that may have adverse affects on the intima (inner lining) of the artery lining, thus creating increased risks for heart and vessel disease. These include: very-low density lipoproteins (VLDLs), low density lipoproteins (LDLs), and triglyderides. VLDL contains tryglyceride, and is a transport and storage form of fat tissue. LDL molecules are the end product of triglyceride metabolism.
High density lipoproteins (HDL), by contrast, has a protective effect against coronary artery disease10,11. HDL particles pick up free cholesterol from cells after esterification of the enzyme lecithin. HDL then transports cholesterol from liver tissue to cells requiring cholesterol or back to the liver for elimination.
The Risk Profile
The National Institutes of Health have produced a risk-statification table that would be of interest to Fitness Therapists, as it may help set guidelines for intensity-dependent workout schedules for persons depending on the severity of their lipid levels. A table is listed below:
| Table 1. Risk Profile for Specific Lipid Concentrations |
|
| | Total Cholesterol |
LDL Cholesterol |
HDL Cholesterol |
Tryglycerides
(all levels in mg/dl) |
|
| High Risk |  245 | 190 | 35 |  1000 |
| Moderate Risk | 221-244 | 160-189 |
36-44 | 500-999 |
| Mild Risk | 201-220 | 130-159 |
45-54 | 250-499 |
| Average Risk | 182-200 | <100-129 |
55-65 | 151-249 |
| Low Risk | <182 | <100 |
65 |
 150 |
|