Citrulline malate is a supplement composed of two molecules with complementary functions: L-citrulline and malic acid. The former, an amino acid found in foods like watermelon, actively participates in the urea cycle, while malic acid is an essential intermediary in the Krebs cycle, facilitating energy production. The combination of these two components has sparked significant interest in both sports and clinical applications.
Origin and composition
L-citrulline is obtained from natural sources and, unlike other amino acids, is not significantly absorbed or metabolized by the liver, allowing it to reach the systemic circulation and be converted into L-arginine in the kidneys. This resulting L-arginine is the essential precursor for nitric oxide synthesis. Malic acid also contributes to the efficient generation of ATP, enhancing cellular energy production during exercise.
Mechanisms of action
Nitric oxide stimulation and improved blood flow
By increasing plasma L-arginine levels, citrulline malate promotes the production of nitric oxide, a biological messenger that induces blood vessel dilation. This process allows for improved oxygen and nutrient delivery to the muscles, which is crucial for maintaining performance during intense activities.
Increase in energy production
Malic acid, a component of the supplement, acts on the Krebs cycle, facilitating the conversion of nutrients into ATP. With greater ATP availability, muscle cells can sustain prolonged or high-intensity efforts, reducing early fatigue.
Optimizing ammonia removal
During vigorous exercise, ammonia buildup can interfere with muscle performance. L-citrulline, by participating in the urea cycle, helps remove this byproduct, contributing to improved metabolic efficiency and delaying fatigue.
Applications in sports performance and recovery
Performance in strength training
Several studies have evaluated the effects of ingesting between 6 and 8 g of citrulline malate before exercise. Some studies have observed that doing so allows for higher repetitions in strength exercises, which translates into greater fatigue tolerance. Although results may vary, evidence suggests that moderate improvements can be seen, especially in workouts involving the lower body.
Post-exercise recovery
In addition to its effects during exercise, citrulline malate has been reported to reduce muscle soreness following an intense session. This ability to mitigate post-exercise soreness could promote faster recovery, allowing for more frequent or intense training in subsequent sessions.
Additional benefits
Beyond its use in sports, this supplement has been studied for its impact on cardiovascular function. By promoting vasodilation, citrulline malate may contribute to blood pressure regulation and improve blood flow in specific clinical conditions. Furthermore, in populations with aging-related muscle loss, its use combined with a balanced diet may promote protein synthesis and muscle preservation.
Dosage and safety
Research has used single doses of 6 to 8 g, administered approximately 60 minutes before physical activity. Short- and medium-term studies have shown that even higher doses are well tolerated, with no significant side effects. Mild gastrointestinal discomfort has been reported in sporadic cases, at levels comparable to those observed in placebo groups.
Challenges and future perspectives
Although citrulline malate shows interesting potential, the variability in study protocols and the quality of available products makes it difficult to draw definitive conclusions. More rigorous research is needed on aspects such as the optimal dose, timing, and response in different population groups. Long-term studies could also clarify whether acute benefits translate into chronic adaptations in strength and muscle mass.
Conclusion
Citrulline malate is a promising supplement that may improve exercise performance and promote faster recovery. Although the observed effects are modest, they can make a difference in certain athletic and clinical settings. Future research is expected to clarify its mechanisms and establish more precise recommendations for its use. Currently, a dose of 6–8 g taken one hour before training is a safe and effective option for those seeking to optimize their performance.