تاثير مصرف حاد ال-كارنيتين بر نقطه شكست تهويه اي و عملكرد ورزشي طي فعاليت فزاينده

The effects of acute L-carnitine administration on ventilatory breakpoint and exercise performance during incremental exercise

Background 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, 2l.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.