COMPARISON OF EXERCISE AND NORMAL VARIABILITY ON HDL CHOLESTEROL CONCENTRATIONS AND LIPOLYTIC-ACTIVITY

In order to compare the influence of a single bout of exercise on HDL- C metabolism with normal variability, 12 male runners (mean age: 24.4 +/- 4 yr) who ran 15 - 30 miles per week underwent exercise (E) and co ntrol (C) experimental conditions. During the E trial subjects ran on a motor driven treadmill at 75 % (42.5 +/- 4.7 ml . kg(-1). min(-1)) V O(2)max until 800 Kcals were expended. The C trial consisted of no exe rcise. Subjects were instructed to follow the same diet and keep a fou r d food diary during each experimental condition, Fasted blood sample s were obtained at the same time of day in each condition at time poin ts corresponding to 24 h pre-exercise (24 PRE), 6 h post- (6 h) and 24 h post-exercise (24 h). Plasma was analyzed for HDL-C, HDL(2)-C and H DL(3)-C (mg . dl(-1)). In addition post-heparin plasma samples were an alyzed for lipoprotein lipase (LPL) and hepatic lipase (HL) activity ( mu mol . FFA(-1). ml(-1)). All values were adjusted far changes in pla sma volume and compared to Baseline. HDL-C levels were unaltered follo wing the C trial. However, following the E trial, HDL-C increased (p < 0.01) above baseline values at 24 h. The increase in HDL-C was reflec ted in the HDL(3)-C subfraction (p < 0.05). Analysis of lipolytic acti vity revealed an overall greater LPL activity (p < 0.05) in the E tria l vs the C trial. In addition, a decrease in HL was observed at 24 h ( p < 0.05) but was not different between experimental conditions. These data suggest that exercise and not normal variability are responsible for alterations in lipolytic activity and corresponding increases in HDL-C levels.