Overweight is associated with abnormalities of lipid metabolism; many of which are reversed by exercise. We investigated the impact of experimental antilipolysis and acute exercise on lipid kinetics and oxidation from VLDL-TG, plasma FFA, and "residual lipids" in overweight men (n=8) using VLDL-TG and palmitate tracers in combination with muscle biopsies in a randomized, placebo-controlled design. Participants received placebo or acipimox on each study day (4h rest, 90min exercise at 50% VO2max). Exercise suppressed VLDL-TG secretion significantly during placebo but not acipimox (placebo-rest: 64.2±9.4, placebo-exercise: 48.3±8.0, acipimox-rest: 55.2±13.4, acipimox-exercise: 52.0±10.9). Resting oxidation of VLDL-TG FA and FFA were significantly reduced during acipimox compared with placebo, whereas "residual lipid oxidation" increased significantly VLDL-TG (placebo: 18±3, acipimox: 11±2 kcal×h-1), FFA (placebo: 14±2, acipimox: 4±0.5 kcal×h-1) and "residual lipid" oxidation (placebo: 3±5, acipimox: 14±5 kcal×h-1). Additionally, during exercise on both placebo and acipimox oxidation of VLDL-TG and FFA increased, but the relative contribution to total lipid oxidation diminished except for FFA, which remained unchanged during acipimox. "Residual lipid oxidation" increased significantly during exercise in both absolute and relative terms. Changes in cellular enzymes and proteins provided no explanations for kinetic changes. In conclusion, suppressed FFA availability blunts the effect of exercise on VLDL-TG secretion and modifies the contribution of lipid sources for oxidation.
- very low-density lipoprotein
- lipid oxidation
- Copyright © 2014, American Journal of Physiology - Endocrinology and Metabolism