Branched-chain amino acids (BCAA) are one of the most popular sports supplements, marketed under the premise that they enhance muscular adaptations. Despite their prevalent consumption among athletes and the general public, the efficacy of BCAA has been an ongoing source of controversy in the sports nutrition field. Early support for BCAA supplementation was derived from extrapolation of mechanistic data on their role in muscle protein metabolism. Of the three BCAA, leucine has received the most attention because of its ability to stimulate the initial acute anabolic response. However, a substantial body of both acute and longitudinal research has now accumulated on the topic, affording the ability to scrutinize the effects of BCAA and leucine from a practical standpoint. This article aims to critically review the current literature and draw evidence-based conclusions about the putative benefits of BCAA or leucine supplementation on muscle strength and hypertrophy as well as illuminate gaps in the literature that warrant future study.

支链氨基酸 (BCAA) 是最受欢迎的运动补充剂之一，其销售前提是它们可以增强肌肉适应能力。尽管 BCAA 在运动员和公众中普遍食用，但 BCAA 的功效一直是运动营养领域争论的焦点。对补充 BCAA 的早期支持源自对它们在肌肉蛋白质代谢中作用的机械数据的推断。在三种 BCAA 中，亮氨酸因其刺激初始急性合成代谢反应的能力而受到最多关注。然而，现在已经积累了大量关于该主题的急性和纵向研究，提供了从实际角度审查 BCAA 和亮氨酸的影响的能力。