Role of exercise and weight loss in maximizing LDL cholesterol reduction

Men and women who exercise regularly exhibit lipoprotein profiles consisten t with their lower incidence of cardiovascular disease. Although serum conc entrations of total cholesterol are seldom markedly lower, exercisers are c haracterized by high concentrations of high-density lipoprotein (HDL) chole sterol and low concentrations of triacylglycerol (TAG) in both fasted and p ostprandial states. Concentrations of low-density lipoprotein (LDL) cholest erol may or may not be lower in endurance-trained individuals than in seden tary controls. Limited evidence suggests that regular exercise may decrease the proportion of small dense LDL. These changes are concordant with exerc ise-induced enhancement of catabolism of TAG-rich lipoproteins, decreasing their residence time in the circulation and hence the opportunity for excha nge of their core lipid with cholesterol-rich lipoproteins. One mechanism m ay be an exercise-induced increase in the activity of lipoprotein lipase in skeletal muscle and possibly adipose tissue. Regular exercise is often, bu t not invariably, associated with loss of body mass and fat mass, compositi onal changes that may contribute to its potential to influence lipoprotein metabolism. However, weight loss alone does not explain these effects and p ersons carrying excess weight can improve the lipoprotein aspects of their cardiovascular risk even in the absence of major weight loss. Evidence exis ts for a dose-response relationship between exercise level and effects on l ipoprotein lipids. A prudent recommendation for an effective regimen is a g ross exercise energy expenditure of 1500 kcal (about 6 MJ) per week. In pra ctical terms, this means walking briskly for about 3.2 km (2 miles) per day .