L-Citrulline is an amino acid that has an important role in the Urea cycle. For those that may not know, the Urea cycle converts high levels of ammonia into urea, a byproduct that’s eliminated from the body. Your workout elevates ammonia which among other things increases muscular fatigue. It also blunts ATP production, which is the energy source used by your muscles when you train. L-citrulline supports muscular energy by helping the body get rid of excess ammonia.
But it does much more than that. Once in the body, citrulline converts into the amino acid l-arginine, which converts into nitric oxide. Once this happens, nitric oxide relaxes blood vessels, allowing greater blood flow to your muscles, and creating extreme muscle cell volume - in other words, the pump.
Why not just take arginine? Because arginine does not absorb as well as citrulline, which bypasses digestion and goes right to the bloodstream. That means that citrulline does a better job of increasing arginine levels in the body than arginine.(1)
If that wasn’t enough, there’s more. It increases nutrient & oxygen delivery to your muscles. This improves exercise performance and between-set recovery.(2,3)