L-Citrulline raises plasma arginine more reliably than oral arginine itself. Increases NO production, vasodilation, and exercise performance. Particularly endurance.
Dose: 6-8g citrulline (or 8g citrulline malate), 30-60 min pre-workout.
Caveats: Looser stools at high doses. Skip the cheap 'citrulline' products that are mostly malate.