Prolab Beta Alanine Extreme fuels your body's ability to increase muscle carnosine synthesis! What is carnosine? Carnosine is composed of beta alanine and L-histidine and your body simply cannot synthesize carnosine without beta-alanine. Carnosine is found in large amounts in Type II or "fast twitch" muscle fibers, which are used in explosive movements like weight training and sprinting. Carnosine helps activate enzymes responsible for generating muscle contractions. Supplementing with beta alanine has shown to significantly delay muscle fatigue to help you squeeze out the last growth stimulating reps.