Effect of Exercise Intensity on Blood Lipid and Lipoprotein Concentrations, Skeletal Muscle Oxidative Capacity, and Body Composition of Rats Fed a High Fat/Cholesterol Diet.

The purpose of this study was to examine physiological mechanisms related to exercise-induced changes in blood lipid and lipoprotein concentrations of aimals on a high fat (10% by weight) and cholesterol (2% by weight) diet. Two excerise intensities were examined which were differentiated relative to peak oxygen consumption (VO(,2))(' )of the rat. The moderate (MOD-EXER) group trained at 70% peak VO(,2)(' ) and the high group (HIGH-EXER) trained at 82% peak VO(,2)(' )throughout the 12-week study. The duration of each daily exercise session was adjusted so that total energy expenditure was not different between the two exercise intensity groups. A pair-fed, cage sedentary control group was used for comparison. Food intake was not different between the HIGH-EXER, MOD-EXER, and control groups during the 12-week period. Following the training period, body weight was lower in the HIGH-EXER group (-44.3 g) than the MOD-EXER group or control. No differences existed in body weight between MOD-EXER and control. Percent fat was lower for the MOD-EXER (-4.4%) and HIGH-EXER (-6.0%) groups compared to control. Lean body mass was lower in the HIGH-EXER group (-11.8 g) compared to the MOD-EXER group, but no differences existed between the two exercise groups and control. Since food intake was equal between exercise and control groups, the lower carcass fat content was due to exercise-induced energy expenditure during and in between training sessions. TOT-C concentration was not different between exercise groups, but was lower in both the MOD-EXER (-72 mg/dl) and HIGH-EXER (-51 mg/dl) group compared to control. HDL-C concentration was also not different between the two exercise groups, yet lower in the MOD-EXER (-29 mg/dl) and HIGH-EXER (-22 mg/dl) groups compared to control. TOT-TG concentration was not different between exercise groups, but the MOD-EXER (-19 mg/dl) and HIGH-EXER (-21 mg/dl) groups were lower than control. Skeletal muscle oxidative capacity was 20% greater in the HIGH-EXER group compared to the MOD-EXER group, and both exercise groups were greater than control. These data indicate that no differences existed in TOT-C, HDL-C, and TOT-TG concentrations between exercise groups training at 70% and 82% peak VO(,2),(' )however, exercise had a pronounced effect compared to sedentary control. These exercise-induced differences were possibly mediated by changes in substrate utilization in skeletal muscle towards a greater reliance on fat and less on carbohydrate.PhDAnimal PhysiologyUniversity of Michiganhttp://deepblue.lib.umich.edu/bitstream/2027.42/159441/1/8314342.pd