Aerobic exercise effects on lipoproteins and tissue lipids in young pigs

Young castrated male pigs were assigned to an exercise or non-exercise group (8 pigs/group). Initial weights were 26 ± 1 kg and 28 ± 3 kg for the non-exercised and exercised groups, respectively. Following a 3-week training period, the aerobic exercise regimen consisted of running 5.3 km/h for 9 min and 4.8 km/h for 20 min on alternate days on a treadmill for 10 weeks. These levels of exercise increased heart rate to approximately 70% of -maximum heart rates obtained by a pretraining maximal stress test. During the first 5 weeks of the experiment (3 weeks of training and 2 weeks of exercise) the pigs were fed a low-fat diet with no added cholesterol. For the remainder of the study, the pigs consumed a high-fat diet with added cholesterol (0.05% of diet). After 10 weeks of exercise, the exercised pigs had 16% less plasma total cholesterol and 21% less unesterified cholesterol and the percentage of cholesterol associated with high density lipoproteins (HDL) increased 33% compared to non-exercised pigs. The relative percentages of low density lipoproteins (LDL) and HDL were also affected by exercise with a 12% decrease in LDL levels and a 16% increase in HDL levels in the exercised pigs. Exercise caused plasma molar lecithin : cholesterol acyltransferase activity to decrease by 26%. Body composition and relative heart weights were similar for both groups at the end of the study. These results show that an aerobic exercise program can significantly affect plasma cholesterol and lipoprotein concentrations.