Scientists at the University of North Carolina found that people who added an hour of mild exercise or 30 minutes of moderate exercise each week had increased levels of good HDL cholesterol.
The study showed exercise produced significant decreases in harmful triglycerides, but only in whites.
Bad LDL cholesterol levels improved in women but not in men.
Added exercise reduced total cholesterol levels only in African American women.
Researchers point to hormonal differences in men and women and genetic differences in race as possible reasons.
The study appears in the Journal of Lipid Research.