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

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Leucine increases anabolic effect of post-training meal by 16 percent

A post-training shake containing whey protein and simple carbohydrates builds more muscle protein if you add leucine, a free amino acid. Human biologists at the University of Maastricht in the Netherlands discovered this when they did an experiment with 8 male students.

The researchers got their subjects, who by the way did not normally do weight training, to train their legs three times by doing leg presses and leg extensions. Immediately after the training session they got a beaker containing about 250 ml of a sports drink, half an hour later another one, and half an hour later again another one Ė and so on, until the subjects had drunk a total of 11 beakers, over a period of 6 hours.

On one occasion the sports drink contained only carbs, on another occasion carbs and whey protein, and on yet another carbs, whey protein and a heavy dose of leucine. [Structure below.]


To be more exact: the researchers gave their subjects 3ml sports drink per kg bodyweight, every half hour. So if you weigh 100 kg youíd drink a total of 3.3 litres of sports drink, containing 110 g protein, 53 g leucine and 165 g carbohydrates.

The researchers wanted to know whether leucine added anything when you already provide your muscles with protein and carbs after a training session. And it did make a difference, the researchers found. They took muscle cell samples from their subjects, and measured the muscle protein build-up [fractional synthetic rate] during the first six hours after the training session.

Adding leucine caused a big rise in the insulin level. The figure below shows the total amount of insulin in the blood during the first six hours after the training session.

The amount of leucine the researchers gave their subjects was high, as you can see in the blood sample measurements. The leucine concentration was ten times higher than that of the other amino acids.

"The additional ingestion of free leucine in combination with protein and carbohydrate likely represents an effective strategy to increase muscle anabolism following resistance exercise", the researchers conclude.

The study provides proof of principle, and shows that itís possible to boost post-training muscle build up if you add leucine to the proteins you consume. The researchers do not specify how much leucine you need to use, although the study suggests that you need to think in terms of big quantities.

We, ignorant reporters, have a suggestion: itís probably not the leucine itself thatís providing the muscles with an anabolic stimulus, but its oxidised analogues. If this is the case, youíll increase the leucine stimulus if you make sure that more leucine oxidises in the muscle cells. So maybe you can gain more effect from less leucine if you take the leucine before you start training. Training with more volume probably results in more oxidation. And, leucine is probably more effective the less carbohydrate and the more protein you consume.

Am J Physiol Endocrinol Metab. 2005 Apr; 288 (4): E645-53.

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