Citrulline is converted to arginine in the body. Taking citrulline increases nitric oxide levels better than taking arginine. Citrulline also removes ammonia from the body increasing endurance and delaying muscle fatigue.
According to Flex Magazine:
"Citrulline malate elevates muscle ATP by 35% during exercise and increases the rate of creatine phosphate resynthesis by 20%."
Take 3-6g of L-citrulline or citrulline malate 30-60 minutes before workouts