The upper panel of this figure displays the average HDL level within each flotation interval for 12 male long distance runners (darker line) and sedentary men (lighter line). The lower panel displays the difference between runners and sedentary men, with the area below the line (light-area) designating the region where the runners had less HDL than the sedentary men (within F1.20 0-1.5), and the area above the line (dark area) designating the region where the runners had more (within F1.202.0-9.0). The runners had less of the denser HDL3, more of the lighter HDL3, and more HDL2 than the sedentary men. Nondenaturing polyacrylamide gradient gel electrophoresis is used to separate HDL particles by size. This technique gives a more