Citrulline is a non-essential amino acid, a precursor of creatine, converted to glycemic amine and arginine. Participates in the synthesis of nitric oxide (NO) by stimulating its production.
Nitric oxide causes capillaries to widen, which in turn increases blood flow. 
Increased blood flow brings a lot of benefits to the muscles undergoing exercise.
The most important benefits of Citrulline Malate supplementation are:

• ·         vasodilatation
• ·         increase the oxygen flow to the muscles
• ·         an increase in nutrient inputs, including creatine to muscle fibers
• ·         strong anti-catabolic effect
• ·         faster regeneration
• ·         faster removal of lactic acid from the muscle (faster and better regeneration)
• ·         faster removal of ammoniac from the blood
• ·         greater production of ATP (adenosine triphosphate) - the primary energy carrier
• ·         directly affects muscle mass and strength