Abstract：The purpose of this study was to investigate the effect of acute oral carnitine supplementation on post-meal glycogen synthesis in exercised human skeletal muscle. Seven healthy male subjects (aged 20.1 ± 0.3 years) completed a 60-min cycling exercise at 70% VO_(2max), and received carnitine or placebo capsules in a cross-over study design. The entire study protocol was repeated after a 7-d washout period. All subjects consumed 2,000 mg carnitine or placebo capsules immediately after exercise with a high carbohydrate meal (2 g carbohydrate/ kg body weight; 80% carbohydrate, 8% fat, 12% protein), and recovered for 3-h after exercise. Muscle biopsy samples were obtained from the vastus lateralis immediately and 3-h after exercise. Simultaneously, blood and gas samples were collected during 3-h recovery period. We found that carnitine supplementation significantly enhanced the muscle glycogen resynthesis rate compared to placebo supplementation. The estimated post-meal insulin response was found to be significantly lower in carnitine supplemented trial compared to placebo trial during recovery. However, no significant differences in blood glucose levels were noticed between the trials. The data from respiratory quotient analysis during recovery showed lower response in carnitine trial, which indicates energy resource in carnitine tails is reliance on fat oxidation. Therefore, this study concludes that acute oral supplementation of carnitine immediately after exercise can enhance the glycogen recovery in exercised human skeletal muscle. (Full text)