A supplement with less than one and a half grams of arginine and the same amount of citrulline makes athletes faster and fitter. Because the two amino acids reinforce each other’s effect, minuscule doses are enough to have a significant ergogenic effect, researchers from the Japanese amino acid producer Kyowa Hakko discovered.
The researchers got 20 fit male football players aged 18-25 on 2 different occasions to cycle as fast as they could for 10 minutes. On one occasion this happened after they had taken a placebo every day for a week. On the day of the test, the subjects had taken the fake supplement one hour before the session.
On another occasion the men received a supplement with 1.2 grams of arginine and 1.2 grams of citrulline.
Arginine and citrulline
According to studies by Kyowa Hakko, arginine and citrulline enhance each other’s effects. In the body, citrulline converts into arginine, and arginine provides NO. NO dilates blood vessels and stimulates the generation of energy in muscle cells by stimulating molecules such as AMPK and PGC-1-alpha.
However, citrulline also inhibits the enzyme arginase in the liver. This enzyme neutralizes arginine molecules before they can provide NO cells in the body.
The amino acid cocktail made footballers faster and enabled them to generate more power.
Although the athletes could pedal harder due to supplementation with the arginine-citrulline combination, they reported less muscle pain after the exercise test than after they had received a placebo. The supplement also ensured that they had experienced the test as less difficult.
“Oral ingestion of citrulline and arginine at doses of 1.2 g / day each for 7 days improved exercise performance in a 10-minute pedaling test and the participants’ subjective perceptions of physical exertion,” conclude the researchers. “Increased NO production induced by elevated plasma citrulline and arginine levels could account for this effect.”