Department of Movement and Sports Sciences, Ghent University, Ghent, Belgium.
Sports Med. 2010 Mar 1;40(3):247-63. doi: 10.2165/11530310-000000000-00000.
Carnosine is a dipeptide with a high concentration in mammalian skeletal muscle. It is synthesized by carnosine synthase from the amino acids L-histidine and beta-alanine, of which the latter is the rate-limiting precursor, and degraded by carnosinase. Recent studies have shown that the chronic oral ingestion of beta-alanine can substantially elevate (up to 80%) the carnosine content of human skeletal muscle. Interestingly, muscle carnosine loading leads to improved performance in high-intensity exercise in both untrained and trained individuals. Although carnosine is not involved in the classic adenosine triphosphate-generating metabolic pathways, this suggests an important role of the dipeptide in the homeostasis of contracting muscle cells, especially during high rates of anaerobic energy delivery. Carnosine may attenuate acidosis by acting as a pH buffer, but improved contractile performance may also be obtained by improved excitation-contraction coupling and defence against reactive oxygen species. High carnosine concentrations are found in individuals with a high proportion of fast-twitch fibres, because these fibres are enriched with the dipeptide. Muscle carnosine content is lower in women, declines with age and is probably lower in vegetarians, whose diets are deprived of beta-alanine. Sprint-trained athletes display markedly high muscular carnosine, but the acute effect of several weeks of training on muscle carnosine is limited. High carnosine levels in elite sprinters are therefore either an important genetically determined talent selection criterion or a result of slow adaptation to years of training. beta-Alanine is rapidly developing as a popular ergogenic nutritional supplement for athletes worldwide, and the currently available scientific literature suggests that its use is evidence based. However, many aspects of the supplement, such as the potential side effects and the mechanism of action, require additional and thorough investigation by the sports science community.
肌肽是一种二肽，在哺乳动物的骨骼肌中浓度很高。它由肌肽合酶从氨基酸 L-组氨酸和β-丙氨酸合成，其中后者是限速前体，由肌肽酶降解。最近的研究表明，慢性口服β-丙氨酸可以显著提高（高达 80%）人体骨骼肌中的肌肽含量。有趣的是，肌肉肌肽负荷导致未经训练和训练的个体在高强度运动中的表现得到改善。尽管肌肽不参与经典的三磷酸腺苷生成代谢途径，但这表明该二肽在收缩肌细胞的动态平衡中起着重要作用，尤其是在高厌氧能量输送率下。肌肽可以通过充当 pH 缓冲剂来减轻酸中毒，但通过改善兴奋-收缩偶联和抵抗活性氧，也可以获得更好的收缩性能。高肌肽浓度存在于快肌纤维比例高的个体中，因为这些纤维富含二肽。女性的肌肉肌肽含量较低，随着年龄的增长而下降，素食者的含量可能更低，因为他们的饮食中缺乏β-丙氨酸。短跑训练运动员的肌肉肌肽含量明显较高，但数周训练对肌肉肌肽的急性影响有限。因此，精英短跑运动员的高肌肽水平要么是一种重要的遗传决定的天赋选择标准，要么是多年训练缓慢适应的结果。β-丙氨酸作为一种流行的运动员营养补充剂，正在迅速发展，目前的科学文献表明，其使用是有证据支持的。然而，该补充剂的许多方面，如潜在的副作用和作用机制，需要运动科学界进行进一步和彻底的研究。
