High-density lipoprotein metabolism in runners and sedentary men
P. N. Herbert, D. N. Bernier, E. M. Cullinane, L. Edelstein, M. A. Kantor and P. D. Thompson
We studied the high-density lipoprotein (HDL) metabolism of five trained
men who ran 16 km daily and five inactive men. Runners were leaner and
their aerobic exercise capacity was much greater. The mean HDL cholesterol
level was 65 mg/dL in the runners and 41 mg/dL in the controls. The
lipid-rich HDL2 species accounted for a much higher proportion of the HDL
in runners (49% v 29%). Tracer studies of radioiodinated autologous HDL
demonstrated that runners did not produce more HDL protein but rather
catabolized less. The mean biologic half-life of HDL proteins was 6.2 days
in the runners compared with 3.8 days in the sedentary men. The activity of
lipoprotein lipase was 80% higher in the postheparin plasma of the runners,
whereas the activity of hepatic triglyceride hydrolase was 38% lower. Thus,
the prolonged survival of plasma HDL proteins in runners may result from
augmented lipid transfer to HDL by lipoprotein lipase or diminished HDL
clearance by hepatic lipase.
