THE ACUTE EFFECTS OF EXERCISE INTENSITY ON HDL-C METABOLISM

To determine whether exercise intensity influences acute HDL-C respons es, 12 male recreational runners (24.8 +/- 4 yr) who ran 15-30 miles.w k(-1) exercised on a motor driven treadmill at 60% (L) and 75% (H) VO2 max. A counterbalanced experimental design was utilized and energy exp enditure was 800 Kcal. Fasting blood samples were obtained 24 h before exercise (24 PRE), immediately post- (IPE), 1 h post- (1 h PE), 6 h p ost- (6 h PE), and 24 h post- (24 h PE) exercise and analyzed for HDL- C and HDL(2&3)-C. In addition, postheparin plasma samples, obtained 24 h PRE, 6 h PE, and 24 h PE were analyzed for lipolytic activity-LPLA and HTGLA. An exercise trial by time interaction was observed for HDL- C (P < 0.01). Post-hoc analysis revealed no change in HDL-C following the L trial. However, an increase in HDL-C was observed 24 h PE (P < 0 .01) following the H trial. The increase in HDL-C was attributed to an elevated HDL(3)-C (P < 0.01), with no change in HDL(2)-C. Analysis of plasma lipolytic activity revealed an increase in LPLA 24 h PE (P < 0 .05) which may be responsible for the postexercise alterations in HDL- C. However, HTGLA decreased 6 h PE (P < 0.01) and 24 h PE (P < 0.05). We conclude that increases in HDL-C levels following endurance activit y are influenced, in part, by the exercise intensity.