| Grant number: | 11/17059-2 |
| Support Opportunities: | Scholarships in Brazil - Post-Doctoral |
| Start date: | June 01, 2012 |
| End date: | January 31, 2014 |
| Field of knowledge: | Health Sciences - Physical Education |
| Principal Investigator: | Antonio Herbert Lancha Junior |
| Grantee: | Guilherme Giannini Artioli |
| Host Institution: | Escola de Educação Física e Esporte (EEFE). Universidade de São Paulo (USP). São Paulo , SP, Brazil |
Abstract Evidences indicate that muscle acidosis is one of the major causes of fatigue in high-intensity exercises. A variety of mechanisms regulates muscle pH, including extracellular buffers, intracellular buffers and dynamic buffering (i.e., efflux of H+ ions to outside the cell). Bicarbonate is the most important extracellular system for the immediate control of pH. Recent studies indicate that carnosine, a dipeptide endogenously sinthesized in muscle from the aminoacids L-histidine and ²-alanine, plays a very important role as an intracellular buffer. The rate-limiting point of carnosine synthesis seems to be the availablility of ²-alanine in muscle. Therefore, ²-alanine supplementation is able to significantly increase intramuscular content of carnosine. Studies show that both ²-alanine (which increases an intracellular buffer) and sodium bicarbonate (an extracelular buffer) are capable of improving performance in exercises of short-duration and high-intensity, is special the intermitent exercises. The purpose of the present study is to investigate whether ²-alanine supplementation has additive ergogenic effects to sodium bicarbonate. Secondary objectives are to explore underlying mechanisms that are possibly involved with the effects of supplementation. About 40 male athletes will take part in the study. They will be randomly allocated into one of 4 groups: ²-alanine + NaHCO3, ²-alanine + placebo, NaHCO3 + placebo, placebo + placebo. All athletes will be assessed PRE and POST the supplementation period (4 weeks of ²-alanine; 1 week of sodium bicarbonate). Performance will be evaluated through 4 bouts of the lower-limbs Wingate Test (30 s of duration at 7.7 kp . kg-1 interspersed by a 3-min recovery period). A familiarization session will take place before the beginning of the study. Before (at rest) and immediately after the 4th bout, blood and muscle samples (from vastus lateralis, using the percutaneous biopsy technique) will be collected, processed and further analyzed. It will be determined: blood pH, plasma lactate and bicarbonate, as well as muscle lactate, glycogen, carnosine and total buffering capacity. We will also determine the expression of the ²-alanine transporter, the carnosine synthetase enzyme and the MCT1 and MCT4. The data obtained will be analyzed with mixed-models ANOVA (proc mixed, SAS v. 9.0). (AU) | |
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