Changes in high density lipoprotein subfractions and other lipoproteins by exercise.

Seventeen previously sedentary men (aged 30-45) were exercised approximately twice weekly over a 10-week period during which time there was a significant fall in low density lipoprotein cholesterol, but total high density lipoprotein (HDL) did not change. The subfraction HDL2 showed an initial fall at two weeks of training with a subsequent rise above the baseline by 10 weeks. HDL3 cholesterol tended to change in an opposite direction to HDL2 thus accounting for no significant change in total HDL cholesterol. Smoking or drinking habits did not change throughout the study. As body weights did not change significantly through the study, energy intake must have increased with probable increased very low density lipoprotein (VLDL) production. Loss of apoprotein C-peptides from HDL2 associated with activation of lipoprotein lipase, and clearance of VLDL, could have caused redistribution of C-apoproteins between HDL3 leading to the changes seen, with the establishment of a new equilibrium with continued training by 10 weeks.