Regular exercise in overweight men and women enhances the improvement in plasma lipoprotein levels that results from the adoption of a low-saturated-fat, low-cholesterol diet.

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We examined the relations of gender and lipoproteins to subclasses of high density lipoproteins (HDLs) in a cross-sectional sample of moderately overweight men (n=116) and women (n=78). The absorbance of protein-stained polyacrylamide gradient gels was osed as an index of mass concentrations of HDL at intervals of 0.01 nm across the entire HDL particle size range (7.2-12 am). At least five HDL subclasses have been identified by their particle sizes: HDL],. (7.2-7.8 nm), HDL a (7.8-8.2 nm), HDL3, (8.2-8.8 nm), HDL2. (8.8-9.7 nm), and HDL^, (9.7-12 nm). Men had significantly higher HDL tt and significantly lower HDLj, and HDL U than did women. Correlations of HDL subclasses with concentrations of other lipoprotein variables were generally as strong for gradient gel electrophoresis as for analytical ultracentrifugation measurements of HDL particle distributions. In both sexes, high levels of HDL],, were associated with coronary heart disease risk factors, including high concentrations of triglycerides, apolipoprotein B, small low density lipoproteins, intermediate density lipoproteins, and very low density lipoproteins and low concentrations of HDL 2 cholesterol and HDL 2 mass. Plasma concentrations of HDL 3 cholesterol were unrelated to protein-stained HDL a levels. HDL 3 cholesterol concentrations also did not exhibit the sex difference or the relations with lipoprotein concentrations that characterized HDL^ Thus, low HDL a levels may contribute in part to the low heart disease risk in men and women who have high HDL cholesterol. In this report, we examine the relations of gender, plasma lipoproteins, and apolipoproteins to proteinstained HDLs in a sample of moderately overweight subjects (116 men and 78 women). The absorbance of protein-stained gels is used as an index of mass concentrations of HDL at intervals of 0.01 nm across the entire HDL particle size range (7.2-12 nm). By examining each diameter value, we are able to identify the regions according to size that are associated with gender and variations in lipid and lipoprotein concentrations without necessarily assuming the shapes or particle size intervals of the HDL subclasses. We also assess whether HDL heterogeneity is adequately represented by HDL 2 and HDL 3 cholesterol measurements. In an "Appendix," we assess the correspondence between estimated HDL particle diameter (gradient gel electrophoresis) and HDL flotation rate (analytical ultracentrifugation), and we compare the lipoprotein correlations obtained for absorbance of HDL protein (gradient gel electro-

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