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
.