Citrulline malate has become a staple ingredient in many pre-workout formulas, prized for both its performance benefits and its role in producing the sought-after muscle “pump.” Here’s what it actually does and how it works.
What Is Citrulline Malate?
Citrulline malate is a combination of L-citrulline, a non-essential amino acid, and malic acid, a compound involved in cellular energy production. While citrulline is also found in foods like watermelon, supplemental doses are considerably higher than what’s typically obtained through diet, and the addition of malate is thought to provide complementary benefits related to energy metabolism.
How It Works
Nitric oxide production. The body converts citrulline into arginine, which is then used to produce nitric oxide, a compound that helps relax and widen blood vessels. This increased blood flow is the basis for the “pump” sensation many people notice during exercise, and it may also support nutrient and oxygen delivery to working muscles.
Interesting note on arginine. Interestingly, supplementing directly with arginine is generally less effective at raising blood arginine levels than supplementing with citrulline, since arginine undergoes significant breakdown in the liver and gut before reaching circulation, while citrulline bypasses much of this and is converted to arginine more efficiently in the kidneys.
Reduced perceived fatigue. Some research suggests citrulline malate may help reduce the buildup of ammonia during exercise and support more efficient energy production, potentially contributing to reduced feelings of fatigue during a workout.
What the Research Shows
Exercise performance. Several studies have found modest improvements in the number of repetitions performed and reduced muscle soreness after resistance training when using citrulline malate, though effect sizes vary across studies and individuals.
Endurance exercise. Some research suggests potential benefits for endurance performance, related to improved blood flow and oxygen delivery, though this area has somewhat more mixed findings compared to resistance training research.
The “pump.” While the subjective sensation of increased muscle fullness during exercise is well-supported by citrulline’s nitric-oxide-boosting mechanism, it’s worth noting that the pump itself is largely a temporary, cosmetic effect rather than a direct driver of long-term muscle growth, even though many people find it a motivating training experience.
Typical Dosing
Most research uses doses of approximately 6–8 grams of citrulline malate, taken 30–60 minutes before exercise. Lower doses used in some commercial pre-workout products (sometimes 1–3 grams) may not match the amounts shown to be effective in supporting research, making it worth checking labels for actual dosing.
Who Might Benefit?
- People engaging in resistance training looking to potentially increase training volume (reps performed) per session
- Those interested in the subjective “pump” sensation during training
- Endurance athletes interested in potential blood flow and oxygen delivery benefits
Safety and Side Effects
Citrulline malate is generally considered safe and well-tolerated at commonly studied doses, with mild digestive discomfort being the most commonly reported side effect at higher doses.
The Bottom Line
Citrulline malate offers reasonable evidence for supporting exercise performance and the muscle pump sensation, primarily through its role in boosting nitric oxide production and blood flow. For those interested in trying it, using doses that actually match research (6–8 grams) rather than the smaller amounts sometimes found in commercial blends will give the best chance of experiencing its studied benefits.
This article is for informational purposes only and is not a substitute for professional medical advice.
