Intense Pre-Workout Nitric oxide precursor. 2 g of leucine per serving. High potency pre-workout. The combination of citrulline and arginine supports nitric oxide production, promoting vasodilation and improving the flow of nutrients and oxygen to the muscles. Caffeine stimulates the nervous system, increases performance and reduces fatigue. Leucine: An essential amino acid that helps reduce muscle loss and promotes muscle recovery after exercise. Glutamine: An important amino acid with anti-catabolic properties that protect muscles during intense workouts, facilitating recovery.