Supplements with performance-enhancing claims are very common. But recently the supplement L-citrulline has received more attention, begging the question does L-citrulline improve swimming performance?
Supplements augmenting nitric oxide are very popular. It has been postulated that augmenting nitric oxide (NO) synthesis through nutritional supplementation may improve muscular function, resistance to fatigue during exercise, and recovery processes after exercise.
Enhanced NO bioavailability may:
- Favorably influence exercise performance through its effects on skeletal muscle and blood vessels.
- Reduce the oxygen cost of exercise, lower the adenosine triphosphate (ATP) cost of muscle contractile force production, improve mitochondrial efficiency, and improve calcium handling
- NO also promotes vasodilation thereby reducing blood pressure and increasing blood flow, which may increase oxygen and nutrient delivery to working muscles and facilitate clearance of metabolic byproducts
L-Citrulline is a nonessential amino acid found primarily in watermelon, cucumbers, and other melons.
Does L-Citrulline Improve Swimming Performance?
Although blood flow enhancement is a proposed mechanism for the ergogenic potential of L-citrulline, evidence supporting acute improvements in vasodilation and muscle tissue perfusion after supplementation is scarce and inconsistent.
Nevertheless, several studies have reported that L-citrulline supplementation can enhance exercise performance and recovery. Based on the current evidence, chronic dosing (.7 days) seems to be more effective than an acute single-dose protocol for enhancing exercise performance. The minimum effective dose seems to be; 3 g/d of L-citrulline, while the maximum effective dose may be as high as 10–15 g/d.
Finally, L-citrulline ingestion 60–90 minutes before the onset of exercise seems to most reliably enhance performance, whether ingested as L-citrulline or citrulline malate. Future studies should continue to investigate the effects of both acute and chronic supplementation with L-citrulline and citrulline malate on markers of blood flow and exercise performance and should seek to elucidate the mechanism underlying such effects.
Reference
- Gonzalez AM, Trexler ET. Effects of citrulline supplementation on exercise performance in humans: a review of the current literature. Journal of strength and conditioning research. 2020;2020 Jan 22. doi:10.1519/JSC.0000000000003426