ĭespite this, beta-alanine supplementation will still increase carnosine concentrations, regardless of low or high baseline levels, with no upper limit for muscle carnosine concentrations having yet been identified. Carnosine concentrations may also decline with age and is most likely influenced by habitual dietary intake of carnosine-containing foods (e.g. Carnosine concentrations tend to be higher in males compared to females, and in fast-twitch compared to slow-twitch muscle fibers. In humans, muscle carnosine contents generally range from 10 – 40 mmol/kg dry weight with average values around 20–30 mmol/kg dry weight, although these contents can be influenced by a number of factors. The variability of increases in carnosine appears to be reflective of baseline levels, with vegetarians having greater increases in carnosine concentrations compared to carnivores. While evidence suggests that athletes engaged in resistance training and high-intensity exercise have higher concentrations of muscle carnosine, longitudinal training studies have demonstrated equivocal changes in intramuscular carnosine. The difference between high and low responders seems, at least in part, to be related to baseline muscle carnosine content and muscle fiber composition. demonstrated that individuals vary in the magnitude of response to 5 to 6 weeks of beta-alanine supplementation (4.8 g/day), with high responders increasing muscle carnosine concentrations by an average of 55 %, and low responders increasing by an average of only 15 %. Doses of 4 to 6 g/day of beta-alanine have been shown to increase muscle carnosine concentrations by up to 64 % after 4 weeks, and up to 80 % after 10 weeks. By itself, the ergogenic properties of beta-alanine are limited however, beta-alanine has been identified as the rate-limiting precursor to carnosine synthesis, and has been consistently shown to increase levels of carnosine in human skeletal muscle. In addition, humans acquire beta-alanine through the consumption of foods such as poultry and meat. Based on the current available literature, the conclusions of the ISSN are as follows: 1) Four weeks of beta-alanine supplementation (4–6 g daily) significantly augments muscle carnosine concentrations, thereby acting as an intracellular pH buffer 2) Beta-alanine supplementation currently appears to be safe in healthy populations at recommended doses 3) The only reported side effect is paraesthesia (tingling), but studies indicate this can be attenuated by using divided lower doses (1.6 g) or using a sustained-release formula 4) Daily supplementation with 4 to 6 g of beta-alanine for at least 2 to 4 weeks has been shown to improve exercise performance, with more pronounced effects in open end-point tasks/time trials lasting 1 to 4 min in duration 5) Beta-alanine attenuates neuromuscular fatigue, particularly in older subjects, and preliminary evidence indicates that beta-alanine may improve tactical performance 6) Combining beta-alanine with other single or multi-ingredient supplements may be advantageous when supplementation of beta-alanine is high enough (4–6 g daily) and long enough (minimum 4 weeks) 7) More research is needed to determine the effects of beta-alanine on strength, endurance performance beyond 25 min in duration, and other health-related benefits associated with carnosine.īeta-alanine is a non-proteogenic amino acid that is produced endogenously in the liver. The International Society of Sports Nutrition (ISSN) provides an objective and critical review of the mechanisms and use of beta-alanine supplementation.
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