L-Citrulline Beats L-Arginine for High-Intensity Performance
by: Robbie Durand
Nitric oxide is made in the body from nitrites and nitrites can be made out of nitrate. Nitric oxide is also made from the amino acid arginine. L-citrulline is a naturally occurring amino acid. L-Citrulline is found in some foods like watermelons and is also produced naturally by the body. L-citrulline is converted into L-arginine and also to nitric oxide. L-citrulline might help increase the supply of ingredients the body needs to making certain proteins. L-Citrulline also help open up veins and arteries to improve blood flow and reduce blood pressure. In short, citrulline is going to help out with getting better pumps in the gym and will enhance performance. For decades, L-Arginine has been the “king” of increasing nitric oxide but according to new research, it seems that L-Citrulline is the new king of pumps for bodybuilders.
Researchers compared the effects of L-citrulline and L-arginine supplementation on nitric oxide (NO) biomarkers, pulmonary O2 uptake (VO2) kinetics and exercise performance. In a randomised, placebo-controlled, cross-over study, ten healthy adult males completed moderate- and severe-intensity cycling exercise on days 6 and 7 of a 7 day supplementation period with placebo (PLA), the athletes were given either:
- 6 grams a day-1 of L-arginine
- 6 grams a day-1 of L-citrulline.
At the end of the study, compared to placebo, plasma [L-arginine] was increased by a similar magnitude with L-arginine and L-citrulline supplementation, but plasma L-citrulline was only increased with L-citrulline supplementation. Plasma nitrite concentration ([NO2–]) was increased with L-arginine, and tended to increase with L-citrulline, compared to placebo; however, mean arterial blood pressure was only lower after L-citrulline supplementation. The steady state VO2 amplitude during moderate-intensity cycle exercise was not significantly different between supplements, but L-citrulline speeded overall VO2 kinetics during severe-intensity exercise, improved tolerance to severe-intensity exercise and increased the total amount of work completed in the exercise performance test. These variables were not altered by L-arginine supplementation.
In conclusion, these results suggest that short-term L-citrulline, but not L-arginine, supplementation can improve blood pressure, VO2 kinetics and exercise performance in healthy adults. The study suggests that during high intensity exercise, only L-citrulline supplementation improved the total amount of work performed.