Effects of L-carnitine acute supplementation on blood lactate levels and the distance run by athletes on treadmill, by the time to reach anaerobic thresholds

Results of previous studies about the effects of L-carnitine supplementation on lactic acid production and improve physical performance during exercise are conflicting. This study was carried out to determine the effect of a single dose of L-carnitine supplement (2 grams in the form of pills), 2 hours before exercise, on blood lactate levels during and after exercise and the distance run by athletes at anaerobic threshold. During a single-blind crossover clinical trial, 12 elite Iranian male Taekwondo players with mean values (±SD) for age, weight, height, body mass index of 19.9±2.0, 71.3±6.4, of 179±4.5, and of 22.0±1.2 respectively were studied. Subjects were randomly assigned to either L-carnitine (n=6) or placebo groups (n=6). The washout period was 72 hours. L-carnitine group received 2 grams of L-carnitine pills dissolved in 200 ml of a sore solution (water containing 6 drops of lemon juice), while the placebo group received 200 ml water flavored with 6 drops of lemon juice. Three blood samples were obtained at 2 hours before, at the end of, and 30 minutes after the end of exercise tests. The exercise tests were carried out according to Conconi protocol on treadmill. Blood lactate levels per meter of distance, from the start to either the end of the exercise or to 30 minutes after the exercise were lower in L-carnitine group (p<0.05), but it did not significantly change in the time interval of 30 minutes after finishing the exercise. The distance run by athletes on treadmill was greater in the L-Carnitine group than the placebo group (1230.8±408.5 and 1045.8±421.9 m) (p<0.01). A significant negative correlation was seen between BMI and the distance run by the athletes, in both groups (r=-0.732, p<0.01 and r=-0.634, p<0.05 in placebo and L-carnitine group, respectively). We concluded that a single dose of L-carnitine supplement, 2 hours before exercise on treadmill, can impede the blood lactate elevation during exercise and thereby improve the physical performance of Taekwondo players.