Exercise-induced changes in plasma lipids and lipoproteins.

Men and women who participate in vigorous endurance-type exercise generally have plasma lipid and lipoprotein profiles consistent with lower risk for coronary heart disease. The major differences from matched physically inactive controls appear to be a lower plasma triglyceride concentration and greater high-density lipoprotein mass, due to increased levels of the subfraction HDL2 and apoprotein A-I. Plasma low-density lipoprotein cholesterol concentration is less likely to be lower than in the inactive controls. Exercise training studies suggest a lower threshold--of around 1,000 kcal per week of endurance-type exercise at moderate intensity--seems to be required to produce plasma lipid or lipoprotein changes. Above this level, dose-response relationship exists, with greater changes occurring up to an expenditure of 4,500 kcal per week. From the limited data available, it appears more difficult to change the plasma lipoprotein concentration in women by exercise training than in men. Modification of activity of enzymes involved in triglyceride and cholesterol synthesis, transport, and catabolism most likely mediates these exercise-induced changes.