The effect of L-carnitine supplementation on plasma glucose and lactate concentrations, and aerobic capacity during submaximal exercise on ergometery cycle

The purpose of this study was to determine the effect of L-carnitine supplementation on glucose and lactate concentrations, and aerobic capacity during sub-maximal exercise on ergometery cycle. In this double- blind clinical trail, 34 healthy noathlete male students at Saveh University were divided into experimental (L-carnitine usage) and placebo (lactose usage) groups and had one trial of cycling on ergometer (PWC170). This trial was done in two stages: 1) Exercise protocol without L-carnitine or placebo supplementation, 2) Exercise protocol with 3g L-carnitine (90 minute before exercise) and placebo supplementation in the experimental and placebo groups, respectively. Immediately after the physical exercise, blood sampling was taken for determining plasma glucose and lactate concentrations, and lactate dehydrogenase activity (LDH). Through polar telemetry rest and sub-maximal heart rate, and also, VO2max were measured. L-carnitine supplementation had no influence on plasma glucose and lactate concentrations. Otherwise, rest and sub-maximal heart rate, VO2max and LDH activity were equal in pretest and posttests. All variables remained with no change in control group. Regarding the effect of L-carnitine usage on performance of endurance exercises, the findings are still vague and controversial. Our findings indicated that ingestion of 3g L-carnitine 90 minutes before exercise did not affect the dependent variables. Further investigation is required to determine the direct effect of such supplementations on substrate utilization, fat-carbohydrate metabolism and performance on exercise.