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Glutamine enhances muscle strengthening effect of leucine

Glutamine enhances muscle strengthening effect of leucine
Supplementation with leucine accelerates muscle recovery and muscle growth more if you also use glutamine. English sports scientists come to this conclusion in a human study, which will soon appear in Amino Acids. It is a pity that the British used extremely high doses that in the long run are bound to cause side effects. Would the leucine-glutamine cocktail also have an effect in moderate doses?

The researchers divided 23 young men into 3 groups. All men did 5 sets of 20 reps drop jumps at the beginning of the experiment. This meant that they jumped from a 60 centimeter raise onto the floor, lowering their thighs until they were parallel to the floor during their landing. In this way, their leg muscles absorbed the impact of the landing.

On days 1, 2 and 3 the researchers determined the how high the men were able to jump.

Just before the drop jumps and afterwards, and just before the tests and just afterwards, the researchers gave the men a glass with 300 milliliters of water and a few dozen grams of maltodextrin.

The placebo group received just that: maltodextrin. The men of the second group received also leucine in the glass; the men in the third group were give a drink with maltodextrin + leucine + glutamine.

The doses were pretty high. An average test subject in the third group received about 17 grams of leucine daily, and 39 g of glutamine. Ugh.

Glutamine enhances muscle strengthening effect of leucine

In the days after the drop jumps, the concentration of creatine kinase in the blood was less high in the men who were using leucine + glutamine. This means that the combination protected against muscle breakdown and accelerated muscle recovery.

Glutamine enhances muscle strengthening effect of leucine

Before and after the drop jumps, the researchers let the test subjects jump as high as possible on several occasions.

The first days after the drop jumps the men jumped less high than before, but supplementation with leucine + glutamine accelerated their recovery. 3 days after the drop jumps the subjects in the leucine + glutamine group jumped even higher than before.

Glutamine enhances muscle strengthening effect of leucine

"It is possible that the effects we have observed are related to the higher energy or amino acid content of the leucine + glutamine group, rather than the specific combination of amino acids", write the researchers. "Similarly, the placebo group did not ingest any additional amino acids outside of their normal diet."

"We opted to investigate a fixed dose of leucine, rather than an iso-caloric dose, to establish whether the effects of the isolated leucine dose could be enhanced. This dose provided an average of approximately 15/day of leucine in the current participants, which was deemed to be suitable, given that 5 g of leucine has been considered as 'high' and sufficient to increase muscle protein synthesis above higher doses of whey protein supplements."

"Nevertheless, our results show that recovery from eccentric exercise, facilitated by acute doses of leucine, can be improved by adding glutamine or additional amino acids to the ingested supplement. Future research should consider adding additional energy- or amino acids-matched groups to the current research design to establish this."

Amino Acids. 2018 May 16. doi: 10.1007/s00726-018-2565-z. [Epub ahead of print].

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