L-citrulline is the natural form of amino acid citrulline. Citrulline helps boost nitric oxide levels to help increase blood flow and deliver nutrients to your muscles, creating the ‘pump’ effect. CORE CHAMPS L-CITRULLINE supports vasodilation through nitric oxide production, helping to improve blood flow and muscle pumps during a workout. L-Citrulline Malate is an amino acid that works to raise both arginine and ornithine plasma levels more efficiently and for longer periods of time than just l-arginine supplementation alone. L-Citrulline is one of the most promising pre-workout supplement ingredients for the purpose of building muscle.