Antwoord Alan Aragon:While I do partially agree with Alan, I do think supplementing BCAA's (especially leucine) could be beneficial. Not WHIT high protein meals (containing sufficient amounts of leucine 3-5gr) but between meals. Lets take a look at the science Alan may be forgotten to mention:
- A complete meal delays and prolongs the anabolic response to a meal approximately 3 hours with a peak in MPS from 45-90 minutes. While both plasma levels and intramuscular leucine concentrations were peaked from 45-180 minutes, and remained elevated above baseline for 5 hours, MPS had returned to baseline at 180 minutes. Furthermore phosphorylation of the mTOR targets 4E-BP1 and S6K were also still peaked at 3 hours and closely followed plasma leucine levels. Thus increases in plasma leucine were able to trigger mTOR signaling and MPS, but sustained elevations of plasma leucine and mTOR signaling were not sufficient to maintain elevated protein synthesis. This suggest a 'refractory' response of MPS to prolonged elevations in plasma amino acids. Bohe et al also documented the refractory nature of skeletal muscle to constant elevations in amino acids during a 6 hour infusion of essential amino acids. The infusion produced constant elevations in plasma EAAs, however, MPS lasted only 2 hours and was unable to be further stimulated during the 6hr period.
This is the so-called "protein stat hypothesis". Note the word hypothesis. In a nutshell, sustained blood amino acid elevations run into a refractory point, where muscle protein synthesis decreases despite the sustained elevation in AAs (& even despite mTOR activation). So, the hypothesis applied within the context of our discussion is that causing quick, marked increases & subsequent rapid drops in extracellular amino acid levels (via dosing free-form AAs) might be able to circumvent this refractory response seen in sustained AA levels.
Sounds good, right? BUT. This is still a hypothesis that's based on acute (immediate-effect, not long-term) and infusion (intravenous) data. We're looking at circumstantial bits & pieces, not a complete picture. This research did not measure effects on size, strength, or muscle retention over the long term. At best, this data is hypothesis-generating, and far from conclusive. Also keep in mind that the literature cited (Bohe et al, 2003) has some fricking hilarious stuff in its conclusion. I'll quote them:
"it appears that only modest amounts of dietary amino acids would be needed to achieve maximal stimulation of the muscle anabolic processes (i.e. for adults of average weight, 55-75 kg, 0.260 mg kg/hr x 2 hr, or of the order of 30-40 g of protein). This is probably somewhat lower than the current FAO/WHO/UNU recommendation of 0.8 g kg/day and much lower than that of 1.2 g kg/day proposed by some workers for the elderly (Campbell et al. 2001)."
^^Check the bold. Bohe et al, who ALWAYS get referenced by the proponents of BCAA dosing in order to avoid the refractory response, don't even have their heads screwed on tightly regarding total protein needs.
Insulin may, at least in part, explain the refractory nature of MPS to constant elevations in plasma amino acids make it seem unlikely that an additional stimulation can be archieved 3 hours post prandially with a second meal of similar composition to the first, as plasma leucine concentrations remain peaked. Thus in order to avoid refractoriness and maximize MPS it may be best t consume larger doses of protein that contain sufficient leucine to maximize mTOR signaling and MPS while allowing enough time (4-6 hours) for post prandial amino acid levels to fall in between meals in order to re-sensitize the system. According to the protein stat theory, a second nutritional intervention which may overcome refractoriness is to create a supraphysiological rise in plasma amino acid levels between meals. A free form amino acid supplement would likely be rapidly digested and empty into the bloodstream quickly, potentially elevating plasma amino acid levels above theri meal induced plateau. Finally it may also be advantageous to consume a carbohyrdate source between high protein meals if insuline in fact play a role in MPS becoming refractory. Evidence for this was provided by Padden-Jones et al. who demonstrated that consuming 30 grams of carbohyrates and15 grams of free form EAA supplement containing ~3g of leucine in between meals spaced 5 hours apart enhanced MPS to unsupplemented subjects fed the same meals. This suggest that supplemental free form AA and CHO may either enhance the anabolic respons to a meal or somehow overcome the refractory response.
The Paddon-Jones study is another commonly cited tidbit by those hanging on to the hope that free-form AA dosing between meals is The Ticket. BUT. The problem is - other than the trial's short-term nature - the treatment imbalance crucially confounds the applicability of the results. The supplemented group ended up with a total of 45g EAA and 90g CHO above and beyond the control group. Does it really surprise you that this group showed greater protein synthesis? Another design flaw that everyone who cites this study misses is that the non-supplemented control group's protein intake totalled 64g for the day, while the supplemented group averaged 109g. It not only was a matter of treatment imbalance, but it essentially became a comparison of insufficient protein intake versus barely adequate intake, even by sedentary standards. Bottom line: you are hinging your beliefs on an optimistic hypothesis that's marketed as Almighty Proven Fact by the supp companies.