the effect of chronic l-carnitne supplementation on plasma glucose and lactate during exercise

background and aim: in skeletal muscle, carnitine plays an essential role in the translocation of long-chain fatty-acids into the mitochondrial matrix for subsequent beta-oxidation. despite an abundance of literature describing the basic mechanisms of action of l-carnitine metabolism, there remains some uncertainty regarding the effects of oral l-carnitine supplementation on metabolism and exercise performance in normal subjects. this study examined the effects of chronic l-carnitine supplementation on glucose and lactate concentration, heart rate and aerobic capacity during submaximal cycling. material and methods: thirty healthy and male students cycled for 20 min at 70% vo2 max before and after 3 weeks (3g daily) l-carnitine (experimental) and placebo (control) supplementation. blood samples were taken immediately after each exercise for the purpose of calculation plasma glucose and lactate concentration, lactate dehydrogenase activity (ldh). a two-way repeated measure anova was used to determine significant differences between the two groups (p<0.05). result: the finding of our study showed that l-carnitine supplementation had no influence on plasma glucose and lactate. also rest and rest heart rate, vo2 max and ldh activity was equal in pre and posttests (p<0.05). all variables were unaffected in the control trial. conclusion: three weeks l-carnitine supplementation had no effect on substrate and carbohydrate metabolism. also, l-carnitine supplementation would be unlikely to be associated with the enhanced exercise performance. key words: l-carnitine, glucose, lactate, metabolism, aerobic exercise conflict of interest: nill received: november 23, 2008 accepted: january 19, 2009