Aerobic exercise has been shown to reduce the risk of cardiovascular disease (CVD). This reduction is proportional to the intensity of the exercise. The reduction in CVD risk is at least partially mediated by changes in circulating lipoproteins resulting from adaptive changes in enzymes involved in their metabolism. Specifically, aerobic exercise is associated with reductions in low density lipoprotein (LDL), total cholesterol and triacylglycerol (TAG), and increases in high density lipoprotein (HDL). Exposure to oxygen can oxidatively damage LDL. Oxidized LDL is a risk factor for atherosclerosis. Although aerobic exercise can cause oxidative damage, there are adaptive changes resulting from chronic exercise that result in lower rather than higher levels of oxidized LDL.