Men who have "low" high-density lipoprotein (HDL)-cholesterol (under 40 mg/dL) are at increased risk for heart attacks. Running is one known method for raising HDL. To determine whether men with high and low HDL-cholesterol benefit equally from running, we examined the cholesterol changes in sedentary men who were assigned at random to lose weight by running (46 men) or to remain sedentary and eat normally (42 control men). This one-year study was lead by Dr. Peter Wood and Dr. William Haskell at Stanford University. In the runners, HDL-cholesterol increased most in men who started out with relatively higher HDL-cholesterol and increased least in those who started out with low HDL. Specifically, those who started with an HDL-cholesterol over 47 mg/dL had an average increase of 7.0 mg/dL after one year, whereas those who started with an HDL under 38 mg/dL had an average increase of only 2.3 mg/dL. Those who started with an intermediate HDL (between 38 and 47 mg/dL) had an intermediate HDL increase (4.9 mg/dL). The larger, more buoyant HDL particles (called HDL2) are thought to offer more protection from heart attacks than the smaller particles (called HDL3). The graph above shows the starting HDL-cholesterol had a more dramatic effect on HDL2 after one year. Specifically, the increase in HDL2-cholesterol was over five-fold greater (5.5 mg/dL) in the men who started with high HDL-cholesterol than who started with low HDL-cholesterol (1.0 mg/dL increase). Men starting out with intermediate