Exercise and Hyperlipidemia

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

The N.C.E.P Guidelines

Whether or not the ingestion of cholesterol (via eggs, high-fat foods, etc.) is the cause of excessive blood levels of choesterol remains controversial. Some persons who eat very little cholesterol-laiden foods have genetically high levels of cholesterol naturally. None the less, the problem of high lipid levels is of enough concern that the US Department of Health and Human Services developed the National Cholesterol Education Program (NCEP) in 1989 to combat the problem in this country. The NCEP recommends a low-saturated fat, low cholestrol diet, with weight loss (when indicated) to control and correct elevated plasma cholestrol levels.

Weight loss is accomplished by a restricted diet, or increase physical activity. Performing more exercise usually increases the levels of HDL. Studies have been performed on athletes and general fitness advocates and most investigations have shown significant changes in the levels of HDL after exercise. It is evident that aerobic conditioning brings about the most significant changes in HDL. Studies are now underway to determine whether or not resistance exercise produces the same types of changes in cholesterol and its sub-components as aerobic training.

The model of exercise programming into a treatment regime for elevated lipid levels would follow a three phase program (such as the cardiac rehabilitation section above). This program should start with an initial phase where supervised training teaches clients the benefits of conditioning and their effects on lipid levels. They will then move to a phase whereby they assume more responsibility for a self-paced program, and the instructor changes in the routine and records outcomes information for medical professionals and payors.

Conclusions

The key for making changes in lipid levels is adherence to a regular routine for the first phase of conditioning so that significant reductions in lipid levels may be achieved in a 2-3 month period, and these changes can be maintained over long periods of time (years). With a small weight loss, lipid recductions and hypertention will probably decrease, as well.

1. American College of Sports Medicine. Guidelines for Exercise Testing and Prescription. 4th edition. Lea and Febiger. 1991.


2. Kalkoff, RK, Kim, HJ, Cerletty, A, Ferrou, CA. Metabolic effects of weight loss in obese subjects: changes in plasma substrate levels, insulin, and growth hormone responses. Diabetes. 20; 83-91, 1971.


3. Katch, FI, McArdle, WD. Nutrition, Weight Control, and Exercise. (3rd ed.). Lea and Febiger Publishers, Philadelphia, PA, 1988.


4. Olefsky, J. Reaven, GM Farquahar, JW. Effects of weight reduction on obesity: Study of lipid and carbohydrate metabolism in normal and hyperproteinemic subjects. Journal of Clinical Investigation. 53;64-76, 1974.


5. Kokkinos, PF, Hurley, Strength training and lipoprotein-lipid profiles: A critical analysis and recommendations for further study. Sports Medicine. 9;5:26672, 1990.


6. Molitch, ME, Oill, P, O;Dell, WD. Massive hyperlipidemia during estrogen therapy. JAMA. 227:522, 1974.


7. Lipid Research Program. The lipid research clinic coronary primary prevention trail results. In: Reduction in incidence of coronary heart disease. JAMA. 251:351-64, 1984.


8. Lopez, SA, et al. Effect of exercise and physical fitness on serum lipids and lipoproteins. Athersclerosis. 20:1-9, 1974.


9. Summary of the Second Report of the National Cholesterol Education Program Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults. JAMA. 269:3015-3023, 1993.


10. Gordon, D.J., Rifkind, B.M. High density lipoprotein: The clinical implications or recent studies. New England Journal of Medicine. 321:1311-16, 1989.


11. Wood, P.D., Stefanick, M.L., Williams, P.T., Haskell, W.L. The effects on plasma lipoproteins of a prudent weight-reducing diet, with or without exercise, in overweight men and women. New England Journal of Medicine. 325:461-66, 1991.