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Regular resistance exercise leads to significant skeletal muscle hypertrophy, which can occur through an increase in protein synthesis, a decrease in protein degradation, or both. While stimulus (i.e., exercise) is important for muscle hypertrophy, nutrient availability plays a critical factor regulating the degree of hypertrophy. Obviously, the muscle's hormonal milieu (insulin, cortisol, testosterone, GH, etc.) also has a major impact on protein synthesis.

It is now clear that protein balance over the muscle remains negative after resistance exercise when only carbs are ingested. In sharp contrast, amino acid ingestion alone significantly increases muscle protein anabolism after resistance exercise. However, consumption of both amino acids and carbs results in much greater effects on muscle protein synthesis, suggesting an interactive effect between insulin, amino acids and resistance exercise.

New Study: Aminos + Carbs = Greatest Muscle Hypertrophy
A recent well-controlled study by Bird and colleagues examined the effects of chronic carb and/or essential amino acid supplementation on hormonal and muscular adaptations in untrained young men. All subjects followed the same supervised, resistance training protocol two times per week for 12 weeks. Following resistance exercise, the subjects consumed either a high-glycemic carb (Gatorade), a essential amino acid (6 grams), a combined high-glycemic carb + essential amino acid supplement, or a placebo containing only aspartame and citrus flavouring. As expected, the results revealed that carb + amino acid supplementation enhances muscular and hormonal adaptations to a greater extent than either carb or amino acids consumed independently. Specifically, carb + amino acid ingestion demonstrated the greatest relative increase in type I muscle fiber cross sectional area. Changes in type II muscle fibers exhipited a similar trend. Also, resistance training resulted in similar decreases in body fat across all groups, suggesting that post-exercise ingestion of high-glycemic carbs do not promote fat accumulation.

From Theory to Practice
While the Bird study indicated one should take in both carbs and amino acids after resistance training, it must be clear that a 6 grams dose of amino acids cannot be optimal for serious gym rats. Based on the best available evidence, I would suggest that a post-exercise drink should contain at least the following ingredients:

1. Fast-acting hydrolyzed whey protein. Whey protein has been singled out as the ultimate source of protein based on an excellent amino acid profile, i.e., it is very rich in essential amino acids. However, you also want that these amino acids are absorbed as rapidly as possible. So, whey protein is the way to go. Extensively hydrolyzed (pre-digested) proteins containing mostly di- and tripeptides are absorbed more rapidly than free form amino acids and much more rapidly than intact (whole) proteins. Protein hydrolysates produced from various sources showed increased amino acid absorption when the propotion of di- and tripeptides was increased. So, in order to maximize absoption rate, the ideal protein hydrolysate should contain mainly tri- and tripeptides. Such a protein hydrolysate seems to produce the most immediate hyperaminoacidemia. In other words, the use of a protein hydrolysate in a post-exercise drink is preferred because it results in a faster increase in blood amino acid concentrations than does intact protein, and in turn the levels of essential amino acids in the blood regulate muscle protein anabolism. In addition, protein hydrolysate ingestion has a strong insulinotropic effect.

2. Fact-acting high-glycemic carbs. High-glycemic carbs (e.g., maltodextrine, dextrose) further increase insulin secretion. Both increased availability of amino acids and increased insulin are important to maximize the muscle protein anabolism. Also, insulin decreases post-exercise muscle inflammation and generation of harmful reactive oxygen species. Furthermore, high-glycemic carbs boost glycogen re-synthesis.

3. A extra dose of key amino acid leucine. This branched-chain amino acid virtually acts as a nutrient signal to stimulate muscle protein anabolism. Together with insulin, leucine coordinates muscle protein synthesis following resistance exercise.

4. Creatine monohydrate. Creatine supplementation can enhance muscle size and strenght responses to resistance training. A mixture of whey hydrolysate-carbs-leucine induces a substantial increase in blood insulin, which maximizes creatine transport into the skeletal muscle.

About 45 minutes later you should take in another meal to maximize post-exercise "anabolic window".

Read original article: Search for the Ultimate Post-Exercise Bodybuilding Supplements: the Anobolic Edge.

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References
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