Long-term administration of l-carnitine to humans: effect on skeletal muscle carnitine content and physical performance

Wächter, Sandra; Vogt, Michael; Kreis, Roland; Boesch, Chris; Bigler, Peter; Hoppeler, Hans; Krähenbühl, Stephan

doi:10.1016/s0009-8981(01)00804-x

Cited by 68 publications

(54 citation statements)

References 48 publications

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“…Similar to our study, also most studies in humans failed to show an impact of carnitine supplementation on total muscle carnitine content and on physical performance (Barnett et al, 1994;Wachter et al, 2002). Recently, however, increased carnitine skeletal muscle concentrations in humans treated with high amounts of carbohydrates to induce hyperinsulinemia have been reported (Wall et al, 2011).…”

Section: Discussionsupporting

confidence: 87%

“…In humans, most studies failed to show a positive effect of carnitine supplementation on physical performance, a finding correlating with the fact that the muscle carnitine content could not be increased by oral or parenteral carnitine supplementation despite elevated plasma concentrations (Brass, 2000). High oral doses of carnitine during several days or intravenous infusion for several hours before exercise failed to show an impact on the physical performance of healthy volunteers or athletes (Barnett et al, 1994;Oyono-Enguelle et al, 1988;Wachter et al, 2002). Recently, Wall and colleagues reported an approximately 20% increase of the carnitine muscle content in human subjects ingesting 80 g carbohydrate and 2 g carnitine tartrate per day (Wall et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

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Effect of carnitine, acetyl-, and propionylcarnitine supplementation on the body carnitine pool, skeletal muscle composition, and physical performance in mice

et al. 2013

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Reprint requestUnfortunately, due to copyright-relatedt issues, we are not able to post the post-print pdf version of our manuscript -in some cases, not even any version of our manuscript. Thus, if you would like to request a post-production, publisher pdf reprint, please click send an email with the request to christoph-dot-handschin_at_unibas-dot-ch (see http://www.biozentrum.unibas.ch/handschin).Information about the Open Access policy of different publishers/journals can be found on the SHERPA/ROMEO webpage: http://www.sherpa.ac.uk/romeo/ Reprint AnfragenAufgrund fehlender Copyright-Rechte ist es leider nicht möglich, dieses Manuskript in der finalen Version, z.T. sogar in irgendeiner Form frei zugänglich zu machen. Anfragen für Reprints per Email an christoph-dot-handschin_at_unibas-dot-ch (s. http://www.biozentrum.unibas.ch/handschin). AbstractCarnitine has key functions in energy metabolism. In most studies in animals or humans, carnitine supplementation did not influence muscle composition and function, but the effects of the carnitine esters acetylcarnitine or propionylcarnitine are not well characterized. We therefore investigated the influence of carnitine, acetylcarnitine and propionylcarnitine on body carnitine homeostasis, energy metabolism and physical performance in mice. Animals were orally supplemented with approximately 2 mmol/kg/d carnitine, acetylcarnitine or propionylcarnitine for four weeks, before being subjected to exhaustive exercise and analysis of skeletal muscle energy metabolism and morphology.In supplemented groups, the total plasma and urine carnitine concentrations were significantly higher than in the control group, whereas the skeletal muscle carnitine content remained unchanged. The bioavailability of supplemented carnitine or acylcarnitines was in the range of 20 to 23% as determined by urinary excretion of total carnitine. The supplemented acylcarnitines were hydrolyzed in the intestine and in the liver before reaching the systemic circulation. Skeletal muscle morphology including fiber type composition was not affected by treatment with carnitine or acylcarnitines. Oxygen consumption by muscle fibers obtained from soleus or gastrocnemius was not different between the groups. The supplementation of carnitine or acylcarnitines had no significant impact on the running capacity and on key substrates of skeletal muscle energy metabolism such as glycogen, ATP, phosphocreatine or creatine.In conclusion, oral supplementation of carnitine, acetylcarnitine or propionylcarnitine is associated with increased plasma concentrations of total carnitine and increased urinary excretion of carnitine, but does not affect the skeletal muscle carnitine content. Accordingly, physical performance, skeletal muscle energy metabolism, and muscle fiber type composition are not affected by high oral doses of carnitine or acylcarnitines in mice.

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Section: Discussionsupporting

confidence: 87%

Section: Introductionmentioning

confidence: 99%

Effect of carnitine, acetyl-, and propionylcarnitine supplementation on the body carnitine pool, skeletal muscle composition, and physical performance in mice

et al. 2013

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“…In healthy persons, the beneficial effects of long-term treatment with L-carnitine on physical performance cannot be explained by an increase in muscle carnitine stores (10). The effects of supplementation on pathologic conditions that affect exercise performance are less clear.…”

Section: Introductionmentioning

confidence: 99%

L-carnitine as an ergogenic aid for patients with chronic obstructive pulmonary disease submitted to whole-body and respiratory muscle training programs

Borghi‐Silva

Baldissera

Sampaio

et al. 2006

Braz J Med Biol Res

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The effects of adding L-carnitine to a whole-body and respiratory training program were determined in moderate-to-severe chronic obstructive pulmonary disease (COPD) patients. Sixteen COPD patients (66 ± 7 years) were randomly assigned to L-carnitine (CG) or placebo group (PG) that received either L-carnitine or saline solution (2 g/day, orally) for 6 weeks (forced expiratory volume on first second was 38 ± 16 and 36 ± 12%, respectively). Both groups participated in three weekly 30-min treadmill and threshold inspiratory muscle training sessions, with 3 sets of 10 loaded inspirations (40%) at maximal inspiratory pressure. Nutritional status, exercise tolerance on a treadmill and six-minute walking test, blood lactate, heart rate, blood pressure, and respiratory muscle strength were determined as baseline and on day 42. Maximal capacity in the incremental exercise test was significantly improved in both groups (P < 0.05). Blood lactate, blood pressure, oxygen saturation, and heart rate at identical exercise levels were lower in CG after training (P < 0.05). Inspiratory muscle strength and walking test tolerance were significantly improved in both groups, but the gains of CG were significantly higher than those of PG (40 ± 14 vs 14 ± 5 cmH 2 O, and 87 ± 30 vs 34 ± 29 m, respectively; P < 0.05). Blood lactate concentration was significantly lower in CG than in PG (1.6 ± 0.7 vs 2.3 ± 0.7 mM, P < 0.05). The present data suggest that carnitine can improve exercise tolerance and inspiratory muscle strength in COPD patients, as well as reduce lactate production.

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“…For example, neither feeding L-carnitine daily for up 3 months [27], nor intravenously infusing L-carnitine for up to 5 h [28], had an effect on muscle total carnitine content, or indeed net uptake of carnitine across the leg [29]. Furthermore, feeding 2-5 g/day of L-carnitine for 1 week to 3 months prior to a bout of exercise, had no effect on perceived exertion, exercise performance, VO 2 max, or markers of muscle substrate metabolism such as RER, VO 2 , blood lactate, leg FFA turnover, and post exercise muscle glycogen content [26].…”

Section: Effect Of Increasing Skeletal Muscle Carnitine Availability mentioning

confidence: 99%

Carnitine and Fat Oxidation

Stephens

Galloway

2013

Nestlé Nutrition Institute Workshop Series

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Fat and carbohydrate are the primary fuel sources for mitochondrial ATP production in human skeletal muscle during endurance exercise. However, fat exhibits a relatively low maximal rate of oxidation in vivo, which begins to decline at around 65% of maximal oxygen consumption (VO 2 max) when muscle glycogen becomes the major fuel. It is thought that if the rate of fat oxidation during endurance exercise could be augmented, then muscle glycogen depletion could be delayed and endurance improved. The purpose of the present review is to outline the role of carnitine in skeletal muscle fat oxidation and how this is influenced by the role of carnitine in muscle carbohydrate oxidation. Specifically, it will propose a novel hypothesis outlining how muscle free carnitine availability is limiting to the rate of fat oxidation. The review will also highlight recent research demonstrating that increasing the muscle carnitine pool in humans can have a significant impact upon both fat and carbohydrate metabolism during endurance exercise which is dependent upon the intensity of exercise performed.

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Long-term administration of l-carnitine to humans: effect on skeletal muscle carnitine content and physical performance

Cited by 68 publications

References 48 publications

Effect of carnitine, acetyl-, and propionylcarnitine supplementation on the body carnitine pool, skeletal muscle composition, and physical performance in mice

Effect of carnitine, acetyl-, and propionylcarnitine supplementation on the body carnitine pool, skeletal muscle composition, and physical performance in mice

L-carnitine as an ergogenic aid for patients with chronic obstructive pulmonary disease submitted to whole-body and respiratory muscle training programs

Carnitine and Fat Oxidation

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