Effect of glycine propionyl-L-carnitine on aerobic and anaerobic exercise performance.
ABSTRACT The purpose of this study was to evaluate the effect of glycine propionyl-L-carnitine (GPLC) supplementation and endurance training for 8 wk on aerobic- and anaerobic-exercise performance in healthy men and women (age 18-44 yr). Participants were randomly assigned to 1 of 3 groups: placebo (n=9), 1 g/d GPLC (n=11), or 3 g/d GPLC (n=12), in a double-blind fashion. Muscle carnitine (vastus lateralis), VO(2peak), exercise time to fatigue, anaerobic threshold, anaerobic power, and total work were measured at baseline and after an 8-wk aerobic-training program. There were no statistical differences (p> .05) between or within the 3 groups for any performance-related variable or muscle carnitine concentrations after 8 wk of supplementation and training. These results suggest that up to 3 g/d GPLC for 8 wk in conjunction with aerobic-exercise training is ineffective for increasing muscle carnitine content and has no significant effects on aerobic- or anaerobic-exercise performance.
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ABSTRACT: L-Ornithine has an important role in ammonia metabolism via the urea cycle. This study aimed to examine the effect of L-ornithine hydrochloride ingestion on performance during incremental exhaustive ergometer bicycle exercise and ammonia metabolism during and after exercise. In all, 14 healthy young adults (age: 22.2±1.0 years, height: 173.5±4.6 cm, body mass: 72.5±12.5 kg) who trained regularly conducted incremental exhaustive ergometer bicycle exercises after -ornithine hydrochloride supplementation (0.1 g/kg, body mass) and placebo conditions with a cross-over design. The exercise time (sec) of the incremental ergometer exercise, exercise intensity at exhaustion (watt), maximal oxygen uptake (ml per kg per min), maximal heart rate (beats per min) and the following serum parameters were measured before ingestion, 1 h after ingestion, just after exhaustion and 15 min after exhaustion: ornithine, ammonia, urea, lactic acid and glutamate. All indices on maximal aerobic capacity showed insignificant differences between both the conditions. Plasma ammonia concentrations just after exhaustion and at 15 min after exhaustion were significantly more with ornithine ingestion than with placebo. Plasma glutamate concentrations were significantly higher after exhaustion with ornithine ingestion than with placebo. It was suggested that, although the ingestion of L-ornithine hydrochloride before the exercise cannot be expected to improve performance, it does increase the ability to buffer ammonia, both during and after exercise.European journal of clinical nutrition 10/2010; 64(10):1166-71. DOI:10.1038/ejcn.2010.149 · 2.95 Impact Factor
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ABSTRACT: Carnitine (L-3-hydroxytrimethylamminobutanoate) is a naturally occurring compound that can be synthesized in mammals from the essential amino acids lysine and methionine or ingested through diet. Primary sources of dietary carnitine are red meat and dairy products; however, commercially produced supplements also are available and have been shown to be safe in humans. Carnitine is stored primarily in skeletal muscle, with lower concentrations in plasma. Biologically, carnitine is essential for the transport of long-chain (carbon chain length = 10) fatty acids across the outer- and inner-mitochondrial membranes (carnitine palmitoyltransferanse I and II, respectively). Conflicting results characterized the early research focused on L-carnitine supplementation's ability to enhance endurance performance, and studies showed no changes occurred in muscle carnitine levels. Nevertheless, promising findings for its use have been observed for various pathologies, including cardiovascular diseases, which show it might mitigate some negative effects and enhance physical function. Recent studies have focused upon a different paradigm for L-carnitine in regulating hypoxic stress and enhancing recovery from exercise.Current Sports Medicine Reports 7(4):218-23. DOI:10.1249/JSR.0b013e318180735c · 1.60 Impact Factor
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ABSTRACT: (Received 31 October, 2009 ; Accepted 10 March, 2010)AbstractBackground and purpose: Many athletes adopt nutritional manipulations to improve their performance. Among the substances generally consumed is carnitine (L-trimethyl-3-hydroxy-ammoniobutanoate) which has been used by athletes as an ergogenic aid, due to its role in the transport of long-chain fatty acids across mitochondrial membranes. Nutritional supplements containing carbohydrates, proteins, vitamins, and minerals have been widely used in various sporting fields to provide a boost to the recommended daily allowance. The aim of this study is to investigate the effects of acute L-carnitine administration on ventilatory breakpoint, an exercise performance during incremental exercise.Materials and methods: This study was double-blind, randomized and crossover in design. The subjects were 12 randomly selected active male physical education students, 21.75±0.64 years old, with a mean body mass index (BMI) of 23.7±0.94kg/m2, divided into 2 groups. They received orally either 2g of L-carnitine dissolved in 200 ml of water, plus 6 drops of lemon juice or a placebo (6 ml lemon juice dissolved in 200 ml of water) 90 minutes before they began to exercise on a treadmill. They performed a modified protocol of Conconi test to exhaustion. One-way analysis of variance with repeated measurements was used for data analysis.Results: The results showed that exercise performance improved in LC group (2980±155 meter) compared with placebo group (2331±51 meter). Furthermore, no significant difference was found in ventilatory breakpoint between the two groups.Conclusion: This finding indicates that administration of L- Carnitine, 90 minutes prior to exercise may improve performance; despite the ventilatory breakpoint as one of the anaerobic system indices that had no effect. J Mazand Univ Med Sci 2009; 19(73): 43-50 (Persian).