Amino acids are the building elements, which are necessary for the synthesis of all kinds of protein molecules, in the human body. They can be classified in two major groups: essential and non-essential. The non-essential amino acids can be synthesized in the human body in enough quantity in order to function properly. The essential amino acids cannot be synthesized by the human body and they must be supplied through food. During highly intensive workouts the human organism requires higher amounts of amino acids, necessary as provisions to the sped up metabolic processes, as well as for the complete recovery of the muscle cells after an intensive workout. The recovery process of myocytes includes increased protein synthesis, a basic for the increasing volume of muscle cells, respectively the volume of the muscle mass. Amino acids are contained in all kinds of meat and dairy products as well in some foods of plant origin. The provision of amino acids from food in appropriate quantity in the appropriate time during an intensive workout is very hard. Hence, the easiest way to supply with amino acids is through supplementation. The intake of appropriate amount of amino acids in the appropriate time provides: normal function of the sped up metabolic processes, muscle recovery, necessary for muscle growth, after a workout, and a protection from disintegration during high volume workouts in calorie deficit. Amino acids are fundamental food supplement in all types of workout programs.