Exercise, protein metabolism, and muscle growth.

Metabolism Division, Department of Surgery, University of Texas Medial Branch-Galveston, Galveston, TX 77550-2720, USA.


Exercise has a profound effect on muscle growth, which can occur only if muscle protein synthesis exceeds muscle protein breakdown; there must be a positive muscle protein balance. Resistance exercise improves muscle protein balance, but, in the absence of food intake, the balance remains negative (i.e., catabolic).

The response of muscle protein metabolism to a resistance exercise bout lasts for 24-48 hours; thus, the interaction between protein metabolism and any meals consumed in this period will determine the impact of the diet on muscle hypertrophy. Amino acid availability is an important regulator of muscle protein metabolism. The interaction of postexercise metabolic processes and increased amino acid availability maximizes the stimulation of muscle protein synthesis and results in even greater muscle anabolism than when dietary amino acids are not present.

Hormones, especially insulin and testosterone, have important roles as regulators of muscle protein synthesis and muscle hypertrophy. Following exercise, insulin has only a permissive role on muscle protein synthesis, but it appears to inhibit the increase in muscle protein breakdown. Ingestion of only small amounts of amino acids, combined with carbohydrates, can transiently increase muscle protein anabolism, but it has yet to be determined if these transient responses translate into an appreciable increase in muscle mass over a prolonged training period.

Protein basics from CDC http://www.cdc.gov/nutrition/everyone/basics/protein.html

The RDA for protein is 0.8 gm/kg body weight for most adults. Vegetarians may need to increase this by 10 percent. Endurance athletes require 1.2-1.4 gm/kg while strength athletes need 1.6-1.7 gm/kg. The elderly require 1.25 gm/kg. Let's take a look at this http://www.uth.tmc.edu/courses/nutrition-module/section1/protein.html

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  • Great information for body builders

  • Yesterday I told a trainer who has told me to be a professional bodybuilder that I'm having stomach ache because I had protein shake during workout. I shared that I uased to have ON Hydro Whey which I was able to take in during workout whereas it's not available in market for a while (how to get much better in India?) and so I'm having ON 100% Whey. The trainer told me that isolate is faster absorbing than hydrolysed protein. I told him that isolate has a lot more protein content but hydrolysed is faster. I also said that I'll search again and that I just read thishttp://sportsnutritioninsider.insidefitnessmag.com/3771/show-me-the...

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    Then there is also hydrolyzed whey protein (also called hydrolyzed whey peptides). When a protein is hydrolyzed is means that it, by technological processes, has been split to smaller chains of amino acids, called peptides 16, 30-33. The hydrolytic process mimics our own digestive actions; thus it can be said that hydrolyzed protein is a predigested protein. Hydrolyzed proteins contain mostly di-peptides and tri-peptides, and are absorbed more rapidly than free-form amino acids and much more rapidly than intact (non-hydrolyzed) proteins 34-46.

    Consumption of whey protein hydrolysate in post-exercise (and before strength training workouts) drinks is preferred because it results in a faster increase in blood amino acid concentrations and a higher insulin response during a 2-3 h period than does intact protein 47-49. The simultaneous increase in blood amino acids and insulin levels in turn significantly promotes muscle protein synthesis and inhibits muscle protein breakdown 50-58.

    It is especially interesting that consumption of protein hydrolysate solutions (that also contain 15 g glucose) result in peak blood insulin concentrations that are two and four times higher than after the ingestion of milk and glucose solutions (15 g glucose in water), respectively 49. This despite the fact the milk dose in that study contained nearly three times more carbohydrate 49.

    Thus, when one consumes protein hydrolysates in post-exercise drinks (and pre resistance exercise) one can create a powerful response in blood amino acids and insulin levels without having to ingest large amounts of carbohydrates and unnecessary calories. Another practical advantage is that one can ingest a protein hydrolysate-containing supplement immediately after exercise without becoming bloated and not excessively suppressing appetite, so one can eat another meal sooner, possibly optimizing the post-exercise “anabolic window”. Have you been frustrated over protein powders that clog your shaker? Then you have an additional reason to get a whey protein powder with hydrolysates because the hydrolysates increase the solubility of the product 32.

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