The protein in our diet gets broken down into amino acids. There are two types of amino acids: essential amino acids, which our bodies cannot make, and non-essential amino acids. Leucine, isoleucine, and valine are among the essential amino acids and are collectively known as the branched chain amino acids. Leucine has several unique metabolic functions. It regulates protein synthesis in muscle tissue, facilitates the uptake of glucose into muscle tissue, and improves whole body glucose metabolism. Other effects of leucine are of particular interest to athletes: leucine is thought to reduce the fatigue associated with endurance exercise and is known to reduce muscle soreness after intense resistance training. While there are no established guidelines for supplementing, most of the benefits can be obtained with a dose of 15-20 g/day in divided doses.