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Modest changes in high-density lipoprotein concentration and metabolism with prolonged exercise training
P D Thompson1, E M Cullinane, S P Sady
1Division of Nutrition and Metabolism, Miriam Hospital, Providence, Rhode Island 02906.
Circulation
|July 1, 1988
Summary
Regular exercise training in sedentary men improves fat metabolism and extends high-density lipoprotein (HDL) survival, modestly increasing HDL cholesterol. These changes enhance fat tolerance but may be limited in magnitude for many individuals.
Area of Science:
- Exercise Physiology
- Lipid Metabolism
- Cardiovascular Health
Background:
- Sedentary lifestyles are associated with unfavorable lipid profiles and cardiovascular disease risk.
- Understanding the impact of exercise on high-density lipoprotein (HDL) metabolism is crucial for cardiovascular health.
- Previous studies suggest exercise training influences HDL cholesterol, but the specific mechanisms and duration-dependent effects require further investigation.
Purpose of the Study:
- To investigate the effects of prolonged exercise training on high-density lipoprotein (HDL) metabolism in previously sedentary men.
- To assess changes in HDL cholesterol, triglycerides, and related enzyme activities.
- To evaluate the impact of exercise on the survival and synthesis rates of HDL apolipoproteins.
Main Methods:
- Eight sedentary men underwent 14 weeks of stationary cycling, followed by 32-48 weeks of continued training.
- HDL metabolism was assessed using 125I-radiolabeled autologous HDL.
- Measurements included maximal oxygen uptake, body composition, plasma lipids, lipoprotein lipase activity, hepatic triglyceride lipase activity, and apolipoprotein half-lives and synthetic rates.
Main Results:
- Maximal oxygen uptake increased significantly after 14 weeks but plateaued thereafter.
- HDL cholesterol increased modestly, while triglycerides decreased after 14 weeks, with no further significant changes.
- Postheparin plasma lipoprotein lipase activity increased, while hepatic triglyceride lipase activity decreased.
- Triglyceride clearance improved, and HDL apolipoprotein A-I and A-II half-lives showed a trend towards prolongation.
- Plasma volume increased, but total and LDL cholesterol, and apolipoprotein A-I and A-II concentrations remained unchanged.
Conclusions:
- Prolonged exercise training in sedentary men enhances fat tolerance and HDL cholesterol by increasing HDL survival.
- The observed changes in HDL apolipoprotein survival were less pronounced than those seen in elite athletes.
- Exercise-induced improvements in HDL cholesterol may be modest and vary among individuals.