Effects of L-carnitine supplementation on metabolic utilization of oxygen and lipid profile among trained and untrained humans

Abstract

© 2016, Sports Medicine Research Center. Background: The effectiveness of L-carnitine supplementation has been met with conflicting findings when used by sedentary and athletic adults. Objectives: This study aimed to investigate the acute effects of L-carnitine supplementation on aerobic metabolic efficiency and lipid profiles in sedentary and athletic men. Methods: Fifteen sedentary (20.4 ± 1.5 years) and 15 athletic (21.5 ± 2.4 years) men were studied in durations of control, placebo intake and 2 g of L-carnitine supplementation. Lipid profiles, including triglyceride, cholesterol, high-density lipoprotein (HDL) and very-low density lipoprotein (VLDL), were determined before and 40 min after either the placebo or L-carnitine intake. Oxygen consumption (direct VO2), ventilatory threshold (VT), and running time (RT) were recorded after a submaximal treadmill exercise test. Results: Direct VO2increased significantly at 80% of maximal heart rate after L-carnitine supplementation in both athletic and sedentary men, whereas, a statistical increase in VT and RT occurred only after L-carnitine use in athletes, when compared to the control and placebo subjects. The sedentary group showed no changes in lipid parameters, but triglyceride levels reduced significantly in the athletes after consuming L-carnitine. Conclusions: Acute L-carnitine supplementation possibly affects exercise performance and triglycerides in athletes rather than sedentary men.