There's no proof that fast digesting proteins cause more muscle growth than slow digesting proteins. Or lets say you take fast digesting proteins around the workout and the rest of the day slow - will it cause more growth than only eating so-called slow proteins? There's no proof of that. I admit that there's some pretty good sounding theories on why fast digesting proteins might be advantageous at certain times (such as if you're training in the morning and have obviously fasted for many hours) - but it's far from proven. Would Levrone have been bigger if he had eaten aminos and powders in place of some of that fish and meat? My guess is no.
Also you can't look at these amino studies in isolation - only looking at acute effects. Sure aminos will boost protein synthesis nicely if taken before a workout but does that mean you'll end up with more net protein synthesis at the end of the day? The body is good at balancing things out... I could compare this to the debate on HIIT cardio vs. steady state cardio. Which is more beneficial for fat loss? It seems that at the end of the day the amount of fat lost is the probably pretty similar. Looking at acute effects on substrate use doesn't tell the whole story since the body balances things out. I'm thinking you can't "force" more muscle growth by spiking with Leucine or what have you. The HMB was a bust and that compound is a leucine metabolite that also stimulates mTor that's so in the rage nowadays.
you are 100% correct van.
here are 3 studies that show slow proteins > fast proteins for protein synthesis and reduced muscle breakdown:
Slow and fast dietary proteins differently modulate postprandial protein accretion.
Boirie Y, Dangin M, Gachon P, Vasson MP, Maubois JL, Beaufrère B.
Laboratoire de Nutrition Humaine, Université Clermont Auvergne, Centre de Recherche en Nutrition Humaine, BP 321, 63009 Clermont-Ferrand Cedex 1, France.
The speed of absorption of dietary amino acids by the gut varies according to the type of ingested dietary protein. This could affect postprandial protein synthesis, breakdown, and deposition. To test this hypothesis, two intrinsically 13C-leucine-labeled milk proteins, casein (CAS) and whey protein (WP), of different physicochemical properties were ingested as one single meal by healthy adults. Postprandial whole body leucine kinetics were assessed by using a dual tracer methodology. WP induced a dramatic but short increase of plasma amino acids. CAS induced a prolonged plateau of moderate hyperaminoacidemia, probably because of a slow gastric emptying. Whole body protein breakdown was inhibited by 34% after CAS ingestion but not after WP ingestion. Postprandial protein synthesis was stimulated by 68% with the WP meal and to a lesser extent (+31%) with the CAS meal. Postprandial whole body leucine oxidation over 7 h was lower with CAS (272 +/- 91 micromol.kg-1) than with WP (373 +/- 56 micromol.kg-1). Leucine intake was identical in both meals (380 micromol.kg-1). Therefore, net leucine balance over the 7 h after the meal was more positive with CAS than with WP (P < 0.05, WP vs. CAS). In conclusion, the speed of protein digestion and amino acid absorption from the gut has a major effect on whole body protein anabolism after one single meal. By analogy with carbohydrate metabolism, slow and fast proteins modulate the postprandial metabolic response, a concept to be applied to wasting situations.
and this one compares fast and slow with identical AA profiles:
The digestion rate of protein is an independent regulating factor of postprandial protein retention.
Dangin M, Boirie Y, Garcia-Rodenas C, Gachon P, Fauquant J, Callier P, Ballèvre O, Beaufrère B.
Laboratoire de Nutrition Humaine, Centre de Recherche en Nutrition Humaine, Université Clermont Auvergne, 63009 Clermont-Ferrand, France.
To evaluate the importance of protein digestion rate on protein deposition, we characterized leucine kinetics after ingestion of "protein" meals of identical amino acid composition and nitrogen contents but of different digestion rates. Four groups of five or six young men received an L-[1-13C]leucine infusion and one of the following 30-g protein meals: a single meal of slowly digested casein (CAS), a single meal of free amino acid mimicking casein composition (AA), a single meal of rapidly digested whey proteins (WP), or repeated meals of whey proteins (RPT-WP) mimicking slow digestion rate. Comparisons were made between "fast" (AA, WP) and "slow" (CAS, RPT-WP) meals of identical amino acid composition (AA vs. CAS, and WP vs. RPT-WP). The fast meals induced a strong, rapid, and transient increase of aminoacidemia, leucine flux, and oxidation. After slow meals, these parameters increased moderately but durably. Postprandial leucine balance over 7 h was higher after the slow than after the fast meals (CAS: 38 +/- 13 vs. AA: -12 +/- 11, P < 0.01; RPT-WP: 87 +/- 25 vs. WP: 6 +/- 19 micromol/kg, P < 0.05). Protein digestion rate is an independent factor modulating postprandial protein deposition.
and another than highlights that fast AA uptake is detremental, and that milk is good
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:
Compared with casein or total milk protein, digestion of milk soluble proteins is too rapid to sustain the anabolic postprandial amino acid requirement.Lacroix M, Bos C, Léonil J, Airinei G, Luengo C, Daré S, Benamouzig R, Fouillet H, Fauquant J, Tomé D, Gaudichon C.
UMR INRA 914, Physiology of Nutrition and Feeding Control Unit, Institut National Agronomique Paris-Grignon, Paris, France.
BACKGROUND: The in vivo quality of milk protein fractions has seldom been studied in humans. OBJECTIVE: Our objective was to compare the postprandial utilization of dietary nitrogen from 3 [(15)N]-labeled milk products: micellar caseins (MC), milk soluble protein isolate (MSPI), and total milk protein (TMP). DESIGN: The macronutrient intakes of 23 healthy volunteers were standardized for 1 wk, after which time the subjects ingested a meal containing MC (n =
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, MSPI (n = 7), or TMP (n =
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. [(15)N] was measured for an 8-h period in plasma amino acids, proteins, and urea and in urinary urea. RESULTS: The transfer of dietary nitrogen to urea occurred earlier after MSPI ingestion than after MC and TMP ingestion, and concentrations remained high for 8 h, concomitantly with higher but transient hyperaminoacidemia and a higher incorporation of dietary nitrogen into plasma amino acids. In contrast, deamination, postprandial hyperaminoacidemia, and the incorporation of dietary nitrogen into plasma amino acids were lower in the MC and TMP groups. Finally, total postprandial deamination values were 18.5 +/- 2.9%, 21.1 +/- 2.8%, and 28.2 +/- 2.9% of ingested nitrogen in the TMP, MC, and MSPI groups, respectively. CONCLUSIONS: Our results confirm the major role of kinetics in dietary nitrogen postprandial utilization and highlight the paradox of MSPI, which, despite its high Protein Digestibility Corrected Amino Acid Score, ensures a rate of amino acid delivery that is too rapid to sustain the anabolic requirement during the postprandial period. Milk proteins had the best nutritional quality, which suggested a synergistic effect between soluble proteins and caseins.
So basically slow beats fast
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