Supplementation of L-carnitine in athletes: does it make sense? (original) (raw)
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REVIEW ARTICLE Supplementation of L-Carnitine in Athletes: Does It Make Sense?
2013
Studies in athletes have shown that carnitine supplementation may foster exercise performance. As reported in the majority of studies, an increase in maximal oxygen consumption and a lowering of the respiratory quotient indicate that dietary carnitine has the potential to stimulate lipid metabolism. Treatment with L-carnitine also has been shown to induce a significant postexercise decrease in plasma lactate, which is formed and used continuously under fully aerobic conditions. Data from preliminary studies have indicated that L-carnitine supplementation can attenuate the deleterious effects of hypoxic training and speed up recovery from exercise stress. Recent data have indicated that L-carnitine plays a decisive role in the prevention of cellular damage and favorably affects recovery from exercise stress. Uptake of L-carnitine by blood cells may induce at least three mechanisms: 1) stimulation of hematopoiesis, 2) a dose-dependent inhibition of collagen-induced platelet aggregatio...
L-Carnitine Supplementation: A New Paradigm for its Role in Exercise
Monatshefte für Chemie - Chemical Monthly, 2005
Early research investigating the effects of L-carnitine supplementation has examined its role in substrate metabolism and in acute exercise performance. These studies have yielded equivocal findings, partially due to difficulties in increasing muscle carnitine concentrations. However, recent studies have proposed that L-carnitine may play a different role in exercise physiology, and preliminary results have been encouraging. Current investigations have theorized that L-carnitine supplementation facilitates exercise recovery. Proposed mechanism is as follows: 1) increased serum carnitine concentration enhances capillary endothelial function; 2) increased blood flow and reduced hypoxia mitigate the cascade of ensuing, destructive chemical events following exercise; 3) thus allowing reduced structural damage of skeletal muscle mediated by more intact receptors in muscle needed for improved protein signaling. This paradigm explains decreased markers of purine catabolism, free radical formation, and muscle tissue disruption after resistance exercise and the increased repair of muscle proteins following long-term L-carnitine supplementation.
l-Carnitine Supplementation in Recovery after Exercise
Nutrients, 2018
Given its pivotal role in fatty acid oxidation and energy metabolism, L-carnitine has been investigated as ergogenic aid for enhancing exercise capacity in the healthy athletic population. Early research indicates its beneficial effects on acute physical performance, such as increased maximum oxygen consumption and higher power output. Later studies point to the positive impact of dietary supplementation with L-carnitine on the recovery process after exercise. It is demonstrated that L-carnitine alleviates muscle injury and reduces markers of cellular damage and free radical formation accompanied by attenuation of muscle soreness. The supplementation-based increase in serum and muscle L-carnitine contents is suggested to enhance blood flow and oxygen supply to the muscle tissue via improved endothelial function thereby reducing hypoxia-induced cellular and biochemical disruptions. Studies in older adults further showed that L-carnitine intake can lead to increased muscle mass accompanied by a decrease in body weight and reduced physical and mental fatigue. Based on current animal studies, a role of L-carnitine in the prevention of age-associated muscle protein degradation and regulation of mitochondrial homeostasis is suggested.
European Journal of Applied Physiology and Occupational Physiology, 1996
A double-blind crossover field study was performed to investigate the effects of acute L-carnitine supplementation on metabolism and performance of endurance-trained athletes during and after a marathon run. Seven male subjects were given supplements of 2 g L-carnitine 2 h before the start of a marathon run and again after 20 km of the run. The plasma concentration of metabolites and hormones was analysed 1 h before, immediately after and 1 h after the run, as well as the next morning after the run. In addition, the respiratory exchange ratio (R) was determined before and at the end of the run, and a submaximal performance test was completed on a treadmill the morning after the run. The administration of L-carnitine was associated with a significant increase in the plasma concentration of all analysed carnitine fractions (i.e. free carnitine, short-chain acylcarnitine, long-chain acylcarnitine, total acid soluble carnitine, total carnitine) but caused no significant change in marathon running time, in R, in the plasma concentrations of carbohydrate metabolites (glucose, lactate, pyruvate), of fat metabolites (free fatty acids, glycerol, ]~-hydroxybutyrate), of hormones (insulin, glucagon, cortisol), and of enzyme activities (creatine kinase, lactate P. Colombani ([2~).
Journal of Exercise Nutrition & Biochemistry, 2018
Studies of L-carnitine in healthy athletic populations have yielded equivocal results. Further scientific-based knowledge is needed to clarify the ability of L-carnitine to improve exercise capacity and expedite the recovery process by reducing oxidative stress. This study aimed to examine the 9-week effects of L-carnitine supplementation on exercise performance, anaerobic capacity, and exercise-induced oxidative stress markers in resistance-trained males. [Methods] In a double-blind, randomized, and placebo-controlled treatment, 23 men (age, 25±2y; weight, 81.2±8.31 kg; body fat, 17.1±5.9%) ingested either a placebo (2 g/d, n=11) or L-carnitine (2 g/d, n=12) for 9 weeks in conjunction with resistance training. Primary outcome measurements were analyzed at baseline and at weeks 3, 6, and 9. Participants underwent a similar resistance training (4 d/w, upper/lower body split) for a 9-week period. Two-way ANOVA with repeated measures was used for statistical analysis. [Results] There were significant increases in bench press lifting volume at wk-6 (146 kg, 95% CI 21.1, 272) and wk-9 (245 kg, 95% CI 127, 362) with L-carnitine. A similar trend was observed for leg press. In the L-carnitine group, at wk-9, there were significant increases in mean power (63.4 W, 95% CI 32.0, 94.8) and peak power (239 W, 95% CI 86.6, 392), reduction in post-exercise blood lactate levels (-1.60 mmol/L, 95% CI-2.44,-0.75) and beneficial changes in total antioxidant capacity (0.18 mmol/L, 95% CI 0.07, 0.28). [Conclusion] L-carnitine supplementation enhances exercise performance while attenuating blood lactate and oxidative stress responses to resistance training.
The Effects of Acute L-carnitine Supplementation on Endurance Performance of Athletes
Journal of Strength and Conditioning Research, 2014
Orer, GE and Guzel, NA. The effects of acute L-carnitine supplementation on endurance performance of athletes. J Strength Cond Res 28(2): 514-519, 2014-This study examined the effect of acute L-carnitine loading on the endurance performance of footballers. Measurements were performed on 26 candidate professional footballers who volunteered to take part in the study. Athletes were given a glass of fruit juice 1 hour before applying L-carnitine with the double-blind method. Then, 12 participants were given 3 g of L-carnitine (LK-3) and the remaining 14 were given 4 g (LK-4). Athletes began the exercise test at a running speed of 8 km$h 21 and then continued at 10 km$h 21 . The speed was increased 1 km$h 21 every 3 minutes, and the test continued until the subject chose to quit. Heart rate was registered using a portable telemetric heart rate monitor during the test. Blood samples were taken from the earlobes of the footballers both before the test and before the speed increase (during the 1-minute interval), and the lactate (La) concentration was measured electroenzymatically. The test was repeated after 1 week as a group of placebos (P-3 and P-4). The result showed that the running speeds corresponding to specific La concentrations were increased, and La and heart rate responses to the running speeds were decreased in both supplemented groups compared with placebos (p # 0.05). A significant reduction in heart rate was found in LK-4 and P-4 (p # 0.05). When the Borg responses to the running speeds were analyzed, a significant difference was found in both supplemented groups (p # 0.05). The results show that 3 or 4 g of L-carnitine taken before physical exercise prolonged exhaustion. . Perceived difficulty according to Borg scale in response to running speeds. When Borg responses to running speeds were examined, significant differences were found between the LK-3 and P-3 groups at running speeds of 8, 11, 12, 13, and 14 km$h 21 , whereas significant differences were also found in Borg responses between the LK-4 and P-4 groups at running speeds of 13, 14, 15, and 16 km$h 21 (p # 0.05).
THE EFFECT OF L-CARNITINE SUPPLEMENTATION ON 1500 m RUNNING PERFORMANCE
2010
SUMMARY The purpose of this study was to determine the effects of L-Carnitine on 1500m running performance and blood lactate level. Healthy and well-trained 20 voluntary male athletes were randomly classified in two groups as the control (n=10) and study (n=10) groups. Before the treatment performance times of the athletes for running 1500 m recorded and the blood samples were obtained four minutes after the exercise. Athletes in the study group were treated with 1 x 2 g of L-Carnitine per day after the lunch for 10 days, while the control group had only fruit juice. Then performance time recording and blood taking were repeated to see the effects of L-Carnitine. The results of the control group showed no statistical significance. But in the study group both performance times and plasma lactate levels significantly reduced (p<0.001). In this study, 10 days L-Carnitine supplementation has provided an ergogenic benefit on blood lactate level and 1500m running performance on well-tr...
The effect of oral supplementation with L-carnitine on maximum and submaximum exercise capacity
European journal of applied physiology and occupational physiology, 1987
Two trials were conducted to investigate the effects of L-carnitine supplementation upon maximum and submaximum exercise capacity. Two groups of healthy, untrained subjects were studied in double-blind cross-over trials. Oral supplementation of 2 g per day L-carnitine was used for 2 weeks in the first trial and the same dose but for 4 weeks in the second trial. Maximum and submaximum exercise capacity were assessed during a continuous progressive cycle ergometer exercise test performed at 70 rpm. In trial 1, plasma concentrations of lactate and [3-hydroxybutyrate were measured pre-and post-exercise. In trial 2, pre-and post-exercise plasma lactate were measured. The results of treatment with L-carnitine demonstrated no significant changes in maximum oxygen uptake (Vo ..... ) or in maximum heart rate. In trial 1, there was a small improvement in submaximal performance as evidenced by a decrease in the heart-rate response to a work-load requiring 50% of I?o .... . The more extensive trial 2 did not reproduce the significant result obtained in trial 1, that is, there was no significant decrease in heart rate at any given submaximal exercise intensity, under carnitine-supplemented conditions. Plasma metabolic concentrations were unchanged following L-carnitine, in both trials. It is concluded, that in contrast to other reports, carnitine supplementation may be of little benefit to exercise performance since the observed effects were small and inconsistent.
Carnitine in Human Muscle Bioenergetics: Can Carnitine Supplementation Improve Physical Exercise?
Molecules, 2020
l-Carnitine is an amino acid derivative widely known for its involvement in the transport of long-chain fatty acids into the mitochondrial matrix, where fatty acid oxidation occurs. Moreover, l-Carnitine protects the cell from acyl-CoA accretion through the generation of acylcarnitines. Circulating carnitine is mainly supplied by animal-based food products and to a lesser extent by endogenous biosynthesis in the liver and kidney. Human muscle contains high amounts of carnitine but it depends on the uptake of this compound from the bloodstream, due to muscle inability to synthesize carnitine. Mitochondrial fatty acid oxidation represents an important energy source for muscle metabolism particularly during physical exercise. However, especially during high-intensity exercise, this process seems to be limited by the mitochondrial availability of free l-carnitine. Hence, fatty acid oxidation rapidly declines, increasing exercise intensity from moderate to high. Considering the important role of fatty acids in muscle bioenergetics, and the limiting effect of free carnitine in fatty acid oxidation during endurance exercise, l-carnitine supplementation has been hypothesized to improve exercise performance. So far, the question of the role of l-carnitine supplementation on muscle performance has not definitively been clarified. Differences in exercise intensity, training or conditioning of the subjects, amount of l-carnitine administered, route and timing of administration relative to the exercise led to different experimental results. In this review, we will describe the role of l-carnitine in muscle energetics and the main causes that led to conflicting data on the use of l-carnitine as a supplement.
2020
Background. In the absence of conclusive data regarding fatigue mechanisms, an important question refers to which stages can improve athletic performance through L-Carnitine intake. Aims. Our aim was to study both blood lactate accumulation and recovery alongside changes in heart rate and heart rate recovery while analysing group performances during physical exercise. Methods. Following one single squat jump test, 16 participants were included in a double blind study by measuring the squat jump performances next to the lactate ([La-]) production and the heart rate response (HR). Lactate accumulation was analysed over four different ocassions, starting with the baseline value and the ending test value (post SJT). Two other [La-] measurements took place during a 40 minute passive recovery stage according to the study groups: L-Carnitine and Maltodextrine use. Results. Following the control study group, during a 20 minute passive recovery stage, [La-] droped to 7.54 mmol/l (6.2 to 9.8)...