Changes in HDL subfractions after a single, extended episode of physical exercise.

In order to investigate the changes in HDL subfractions induced by a single period of extended physical exercise, 9 endurance-trained adults were examined before and 6 min, 1 and 6 h after a 30 km cross-country race. In contrast to less evident changes in the concentrations of total HDL, apolipoprotein A-I and A-II, there were significant changes in HDL subfractions. Resting levels of protein and cholesterol content of the HDL subfractions 1-3 increased (subfraction 1, density gradient 1.093: 1.68 +/- 0.58 to 3.24 +/- 0.86 mmol/1 cholesterol, P less than 0.001), while the concentrations in HDL subfractions 11-12 decreased proportionately (subfraction 12, density gradient 1.142: 3.68 +/- 0.81 to 2.19 +/- 0.22 mmol/1 cholesterol, P less than 0.001). The results suggest that physical exercise induces an increased formation of HDL particles of lower density from HDL particles of higher density. It was concluded that this formation is related to the catabolism of triglyceride-rich lipoproteins in the post-exercise period.