The evidence from cross-sectional studies in men suggest that aerobic exercise may induce an increase of 5%-10% in HDL-cholesterol, primarily the HDL2 subfraction, and decrease the triglycerides. Additionally, some studies found a decrease in LDL-cholesterol and total cholesterol. These changes are dependent on the intensity and frequency of physical activity. Short-term studies show that baseline fitness affects the lipid response to exercise. Changes in lipids induced by a single exercise session persist about 48 hours, which has implications for the timing of lipid testing (Williams, 1997 [D]).

Interpretation of the data from some studies of exercise in women is complicated by the lack of control of the hormonal status. In the NRHS study of women runners, HDL-cholesterol increased irrespective of menstrual status. Interestingly, women using oral contraceptives in this study had a blunted increase in HDL-cholesterol induced by exercise. Not only whether an individual is menopausal, but also the timing of the studies relative to the menstrual cycle affect the outcome. Cross-sectional studies continue to show a beneficial effect in HDL-cholesterol; however, interventional studies in pre- and postmenopausal women fail to consistently show a significant change in HDL-cholesterol (Taylor, 1993 [R]; Williams, 1996 [D]).