EXERCISE TRAINING HAS LITTLE EFFECT ON HDL LEVELS AND METABOLISM IN MEN WITH INITIALLY LOW HDL CHOLESTEROL

Low concentrations of high-density lipoprotein cholesterol (HDL-C) are a recognized risk factor for atherosclerotic cardiovascular disease. Exercise is often recommended to increase HDL-C, but the effect of exe rcise training on HDL levels and metabolism in subjects with low HDL c oncentrations is not well defined. The present study compared the HDL response to 12 months of supervised endurance exercise training withou t weight loss in 17 men aged 26-49 years with initially low (< 40 mg/d l, N = 7) or normal (> 44 mg/dl, N = 10) HDL-C levels. HDL-C levels an d HDL apolipoprotein metabolism were assessed while the subjects consu med controlled diets before and after the year of training. Increases in total (5.1 +/- 2.8 versus 1.9 +/- 4.2 mg/dl, P = 0.08) and HDL2 (3. 8 +/- 2.9 versus 0.4 +/- 1.1 mg/dl, P = 0.01) cholesterol were greater in men with normal initial HDL-C levels. Catabolic rates for HDL apol ipoproteins decreased 7-14% and biological half-lives increased 10-15% after exercise training in subjects with normal HDL, but were unchang ed in the low HDL-C group. HDL apolipoprotein synthetic rates were not consistently affected by exercise training in either group. Posthepar in lipoprotein lipase activity increased 27%, the clearance rate of in travenous triglycerides increased 14%, and apolipoprotein B levels dec reased 16% with training in subjects with normal HDL-C but were unchan ged in the low HDL-C group. We conclude that the ability to increase H DL-C levels through endurance exercise training is limited in subjects with low initial HDL-C, possibly because exercise training in such su bjects fails to alter triglyceride metabolism. (C) 1998 Elsevier Scien ce Ireland Ltd. All rights reserved.