Citrulline malate: How does it work? And can it improve exercise performance? Original paper

Citrulline malate (CM), a combination of L-citrulline and malate, has been touted as an ergogenic (energy-enhancing) aid for resistance training and high-intensity exercise. This narrative review provided a summary of the benefits and uses of CM.

This narrative review described how CM could increase performance, dosage and timing strategies, safety, and effectiveness.

Mechanisms: L-citrulline is a precursor to nitric oxide (NO), a vasodilator, which can improve the delivery of blood and oxygen to and from the muscles during exercise. However, the evidence to date suggests that enhanced blood flow is not the active mechanism for CM's ergogenic effects. Instead, it might be due to citrulline's ability to assist ammonia elimination during high-intensity exercise, malate's ability to increase ATP production, an increase in gene expression, or increased efficiency of the malate-aspartate shuttle.

Dosing and timing: Most research to date has used an acute dose of 8 grams of CM one hour before exercise. While taking CM one hour before exercise remains the best recommendation, some evidence suggests that larger doses of up to 15 grams could be more beneficial.

Safety: Ingestion of a range of CM doses (2–15 grams) has been demonstrated to have no adverse effects on hematological markers. Although the safety of long-term CM supplementation warrants further investigation, research to date indicates that CM is well tolerated in most individuals.

Effects on exercise performance: Preliminary research suggested that 8 grams of CM ingested one hour before exercise enhanced muscular endurance (repetitions to failure) in men and women. However, more recent research has suggested that CM might not have a performance benefit for resistance training performance, potentially due to variations in timing and dosage.