Nitric oxide is a powerful neurotransmitter that helps blood vessels relax and also improves circulation. Supplementing with l-arginine allows your body to use accumulated fats as a source of energy. The accumulated fat is burnt to produce energy and to aid in muscle mass formation and development. L-arginine thus boosts your body metabolism as well as forms building blocks for muscle formation.L-arginine helps bodybuilders to enhance the muscle-swelling pumps so they can perform, recover and grow bigger. L-arginine supports exercise endurance & intensity.