Definition: "An ergogenic aid is any substance or phenomenon that enhances performance "

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More stamina with 3 g L-arginine-L-aspartate per day

Imagine your body being able to take up more oxygen, and burn less sugar and more fat. According to a study done at the University of Innsbruck in 2005, this is the effect of L-arginine-L-aspartate supplementation. Just what the endurance athlete needs.

According to field studies done in the seventies, L-arginine-L-aspartate [structural formula shown below] is a surprisingly effective performance-enhancing substance. But how the supplement works was not investigated at the time.


L-arginine lowers the concentration of lactic acid in the blood during physical exercise. It raises the aerobic capacity of the body, probably by increasing the blood supply to the body's cells. L-arginine is a precursor of NO, which widens blood vessels [vasodilation for the technically minded]. It is believed that NO stimulates the cells uptake of glucose and inhibits the conversion of proteins into glycogen.

L-aspartate increases fat burning and reduces glycogen burning in muscle tissue, in theory. L-aspartate is a direct precursor of oxaloacetate. Oxaloacetate is released during the citric acid cycle, a complex universal reaction in which energy is generated from fats, carbohydrates and proteins.

More stamina with 3 g L-arginine-L-aspartate per day
In theory, L-arginine and L-aspartate mutually reinforce each other's effect. L-arginine saves glycogen and increases oxygen consumption, L-aspartate ensures that more fat is oxidised. The researchers set up an experiment to find out if this is actually what happens. They gave sixteen students a daily dose of 3 g of L-arginine-L-aspartate for three weeks and got them to cycle on an ergometer. The students had to cycle for three minutes at a speed that generated 150 watts no more and no less. This meant the researchers could test the effect of L-arginine-L-aspartate on short sub-maximal exercise.

An equal-sized group of students were given a placebo for the three weeks.

At first the supplement lowered lactate levels. See the figure above. The top of the two figures shows the results of the experimental group; the lower of the two shows the results of the placebo group. Pre-test = before the test, re-test = after.

The table below shows the other effects of L-arginine-L-aspartate on the test subjects' bodies.

More stamina with 3 g L-arginine-L-aspartate per day

Fat burning increases slightly, carbohydrate burning decreases slightly.

L-arginine is the most frequently used NO-booster, but it is perhaps not the most effective. L-citrulline has a better track record. And an alternative for L-aspartate is L-malate. L-citrulline-L-malate used to be marketed as Stimol. It was popular with cyclists in the seventies and reappeared on the market as a supplement.

Journal of Sports Science and Medicine (2005) 4, 314-22.