Endurance and resistance exercise: acute postprandial responses and chronic training adaptations

Abstract

We investigated effects of two exercise modalities on postprandial triglyceride (TG) and free fatty acid (FFA) metabolism. Sedentary, obese women were studied on 3 occasions in randomized order: Endurance exercise for 60 min at 60-65% VO2peak (E), ~60 min high-intensity resistance exercise (R), and a sedentary control trial (C). After exercise, a liquid mixed meal containing [U-C]palmitate was consumed and subjects were studied over 7 hours. Isotopic enrichment (IE) of plasma TG, plasma FFA, and breath carbon dioxide, compared with meal IE, indicated contribution of dietary fat to each pool. Total and endogenously derived plasma TG content was significantly reduced in both E and R compared to C (P < 0.05) with no effect of exercise on circulating exogenous (meal-derived) TG content. Exogenous plasma FFA content was significantly increased following both E and R compared with C (P < 0.05), while total and endogenous FFA was elevated only in E (P < 0.05) compared with C. Fatty acid oxidation rates were significantly increased after R and E as compared with C (P < 0.05) with no difference between the exercise modalities. The results reflect integration of TG and FFA metabolism following exercise. The present results indicate that R and E may be equally effective in reducing plasma TG levels and enhancing lipid oxidation. Importantly, tracer results indicated that the reduction in postprandial lipemia after E and R exercise bouts is not achieved by enhanced clearance of dietary fat, but rather is achieved by reduced circulating abundance of endogenously produced TG.