Liquid Amino Acids are dietary supplements that contain free amino acids or hydrolyzed peptides dissolved in an aqueous solution. Their liquid form differentiates them from powders and capsules, offering immediate availability and rapid absorption from the gastrointestinal tract. They are widely used in sports and clinical nutrition, especially in situations of increased need for immediate supply of amino acids. At a biochemical level, liquid amino acids are already in a dissolved state, which bypasses the dissolution stage and reduces digestion time. Depending on their composition, they may contain essential amino acids (EAA), branched-chain amino acids (BCAA) or a full spectrum of amino acids. After absorption, amino acids immediately enter the circulation and are used as building blocks for muscle protein synthesis, as well as regulatory molecules in metabolic and hormonal processes. One of the main advantages of liquid amino acids is their speed of action. The rapid increase in plasma amino acid levels can help reduce muscle catabolism and maintain a positive nitrogen balance, especially when consumed before or during intense exercise. At the same time, when they contain an adequate amount of leucine, they can activate the mTOR anabolic pathway, supporting muscle protein synthesis. From an ergophysiological perspective, liquid amino acids have been associated with improved recovery, reduced muscle fatigue, and better endurance during exercise. Their ease of consumption and the absence of the need for mixing make them practical for times when solid or viscous liquid food is not desirable, such as during or immediately after exercise. Overall, liquid amino acids are a functional and scientifically proven supplement, with the main advantages of rapid absorption, immediate metabolic availability and ease of use. They are mainly aimed at high-performance athletes, people with increased catabolic stress, as well as those seeking quick and effective support for muscle function, recovery and overall protein adequacy.