Effects of exercise intensity on postprandial lipemia and postheparin lipoprotein lipase activity

Thirteen healthy males (age 23.8 ± 0.9 yrs) participated in three random-ordered trials performed at least a week apart: two exercise trials, which were completed one hour before a high fat meal (1.3 g of fat per kg of body weight), and a control (CON), fat meal only, trial. In the exercise trials subjects walked at low (25% VO₂peak—LOW) and moderate (65% VO₂peak—MOD) exercise intensities, until they expended 1100 kcals. Venous blood samples were obtained about five hours before the high fat meal (12 hours fasted baseline), at 0h (just before the fat meal), and at 2h, 4h, 6h, 8h and 20h after the fat meal for the determination of plasma triglyceride (TG), glycerol, insulin, total cholesterol, high density lipoprotein cholesterol (HDL-C), HDL₂-C, HDL₃-C, as well as blood glucose. Also, blood samples were collected on a separate day (12 hours fasted baseline), and at 8h and 20h during the trials, for the determination of postheparin lipoprotein lipase activity (LPLA) and hepatic TG lipase activity (HTGLA). Postprandial lipemia (area under the plasma TG curve over the 8-hour postprandial period adjusted to the baseline TG value) in the MOD trial was lower when compared to that in either the CON or the LOW trial (p < .05), while there was no statistically significant difference in postprandial lipemia between CON and LOW trials. Postprandial insulinemia was lower in the MOD trial when compared to that in the CON trial, but no other differences between trials were found. LPLA did not change overtime in the CON trial, but it was elevated at 8h in the LOW trial and at 20h in the MOD trial when compared to baseline. Between trials, LPLA at 8h was higher for the LOW trial when compared to that in either the CON or the MOD trial, while at 20h there were no differences between trials. These results suggest that the intensity at which a pre high-fat meal exercise is performed affects postprandial lipemia, and that this effect does not appear to be a result of changes in LPLA as measured in postheparin plasma.