Citrulline
Citrulline is a non-essential amino acid found naturally in watermelon and now the gold-standard pump ingredient in modern pre-workouts. It converts to arginine in the kidneys, raising nitric oxide more effectively than oral arginine itself.
Why It Matters
When you take arginine orally, much of it is broken down by enzymes in the gut and liver before it can raise nitric oxide. Citrulline bypasses that process. It gets absorbed intact, travels to the kidneys, and is then converted to arginine with much higher bioavailability. The result is a stronger pump, better nutrient delivery, and (according to several trials) slightly more reps in the tank.
Citrulline is typically dosed at 6 to 8 grams of pure L-citrulline or 8 grams of citrulline malate per pre-workout serving. Underdosing is the most common reason a pump formula feels weak.
How to Spot It on a Label
Look for L-citrulline or citrulline malate (a 2:1 ratio of citrulline to malic acid). Effective doses are 6 to 8g of free-form citrulline or 8g of citrulline malate. Anything below 3g per serving is sub-clinical and mostly window dressing.
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