Sunday, June 17, 2012

80% Greater Protein Synthesis 3-5h After Workout: 20g+ PWO Protein Threshold Holds. Spiking Lower Amounts With Leucine or EAAs Will Still Yield Sub-Optimal Results

Image 1: Milk (proteins) are not just leucine or EAA - try doing that with half the amount of free-form aminos in water - the results will certainly be "suboptimal", I can vouch for that  ;-)
It has been a while since the last study from Stuart Phillips group at the McMaster University has made it to the SuppVersity news. Their latest publication does yet have the potential to pour oil on troubled waters, because the results appear to confirm that even when every other supplement appears to be failing you, you can always rely on your postworkout whey protein (Churchward-Venne. 2012). And while the study confirms that with some free form amino acid witchcraft, you can actually illicit identical post-exercise increases in protein synthesis, the previously determined threshold dosage of 20g of high quality protein is still the gold standard, for everyone whose interest is to actually build muscle which is, as you as a seasoned SuppVersity veteran know, not happening only in the first hour after a workout but within a 24h+  "window of opportunity" that has the size of barn door (cf. "Opening the 'Anabolic Barn Door' With the Key of Exercise and Nutrition Science!")!

You won't get a-whey without 20g+ of whey!

To elucidate whether the increasingly popular practice of pimping whole proteins with amino acids does make any sense in terms of being able to get away with less total protein, yet identical increases in post-workout protein synthesis Churchward-Venne et al. recruited 24 recreationally active, young adult male volunteers (22±0.6 years; 1.80±0.02m; 76.4±2.0 kg; BMI 24.3kg/m²), who had to perform a standardized 4x4 unilateral leg-workout with 3 min rest between sets consisting of
  • 4x 10-12 reps of seated knee-extension and 
  • 4x 10-12 reps of leg-press
at ~95% of their individual 10-rep max, which had been determined in a testing session 14 days prior.
Note: The reason Churchward-Venne et al. decided to use a unilateral exercise protocol was that this allowed them to take biopsies from both the exercised and non-exercised leg and thus determine the individual influence of exercise and supplementation.

You better make sure you get your protein, not just EAAs or leucine

Figure 1: Amino acid compositions of the test drinks (Churchward-Venne. 2012)
The study participants, who had consumed a standardized, prepackaged relatively low-protein diet (15% protein,. 55% carbohydrate, 30% fat) the day before the exercise intervention, were randomly assigned to consume one of the following drinks
  • whey protein - 25 g whey protein isolate (total leucine: 3g)
  • whey + leucine: 6.25 g whey protein isolate supplemented with free-form leucine (total leucine: 3g)
  • whey + EAA: 6.25 g whey protein isolate supplemented with free-form EAAs (total leucine: 0.75g)
The 300ml of fluid which contained identical tracers, were consumed immediately post workout, blood and muscle biopsies were taken at regular intervals pre- and post workout and MPS, signaling through mTOR, and amino acid transporter (AAT) mRNA abundance were determined.
Figure 2: Relative expression of p-mTOR (left) and p70S6K (right) compared to baseline (Churchward-Venne. 2012)
Now what is interesting is that the "classic" markers of protein anabolism, p-akt (not shown, but exhibited significant differences between treatment), mTOR and P70S6K (figure 2 & 3) do not show a clear-cut advantage of either of the treatments. Immediately post exercise, the increase in mTOR in the exercised leg, for example, is significantly more pronounced in those subjects who consumed a whey protein shake. The "downstream" activation of p70S6K, which supposedly controls protein synthesis at the ribosome, however, is identical in all groups.
Figure 3: Pseudo (=simply weighed by the timespan) area under the curve (a.u) for mTOR and p70S6K, AUC for leucine (a.u.) and fractional protein synthesis in the exercised leg 3-5h after the workout (based on Churchward-Venne. 2012)
The same is true for the protein synthetic response measured as fractional protein synthesis in the whole post exercise period in the untrained, and up to 3h post exercise in the trained leg. Then, however, we see a markedly higher influx of protein into the trained muscle in the whey protein group, which is - and this is somewhat remarkable - not in accordance with the p70S6K levels, which would suggest that the protein influx should be maximal in the leucine and not in the whey group.

A protein pump without protein is useless

Based on the data we have, it is difficult to say whether it is the lack of an individual, a certain combination or the total amount of (non-)essential amino acids that is responsible for this affect. If you take a look at the amino acid composition of the test solutions in figure 1, it does yet appear likely to assume that it is the absence of non-essential amino acids...what? Glutamin? No, I thought so as well, but when you come to think about it, glutamine, of which we have recently seen that it does play a hitherto under-appreciated role in protein synthesis, is unlikely to exert this effect on its own. After all, Chiu et al. based their conclusions with respect to the necessity of glutamine to maximize protein synthesis on increases in mTOR expression (cf. "A New Role for Glutamine in Protein Synthesis?"). 3-5h after the workout the initially increased mTOR levels in the whey protein group had yet returned to baseline and the the leucine, BCAA and EAA levels in the blood of the subjects were identical in all groups (data not shown); and still, the influx of protein into the exercised leg musculature of the whey group was ~80% higher than that in the EAA group.

Image 2 ( Subjects from the EAA, the leucine and the whey group (from left to right) after ingestion of the respective fluids - just kiddin' *rofl*
But let's be honest, in the end, these results only what common sense should have told us all along: You can push the gas pedal as much as you want (leucine group) and still won't get very far if your protein tank is half empty. Similarly, you can ingest as much leucine as you want and it will still have little effect on total protein synthesis, regardless of whether you train or not. For the practitioner, any further speculations about the minimal amount of leucine, a given persons in a given age-group would need to maximally stimulate protein synthesis, as the authors make them in their discussion of the results are non-significant compared to the following straight forward take home messages:
  1. 20-25g of whey protein are still the go to post-workout protein source
  2. building a better post workout protein from free form EAAs is not feasible
  3. the importance of the non-essential amino acids in "real" protein is probably under-appreciated
  4. the importance or I should say potency of leucine is probably much over-estimated
  5. muscle protein synthesis and thus skeletal muscle hypertrophy is not a 2h post workout game
In essence, it would suffice to remember just (1) and (5) and to follow the simple yet effective maxime to get 20g+ of quality protein (not 20g leucine ;-) with every meal to get big and muscular and, as all of you who read yesterday's news or one of the many previous posts in which I envoked the findings of Loenneke et al. which show just that: People with a frequent intake of quality protein have the lowest body fat levels (Loenneke. 2012).

  1. Chiu M, Tardito S, Barilli A, Bianchi MG, Dall'asta V, Bussolati O. Glutamine stimulates mTORC1 independent of the cell content of essential amino acids. Amino Acids. 2012 May 8. [Epub ahead of print]
  2. Churchward-Venne TA, Burd NA, Mitchell CJ, West DW, Philp A, Marcotte GR, Baker SK, Baar K, Phillips SM. Supplementation of a suboptimal protein dose with leucine or essential amino acids: effects on myofibrillar protein synthesis at rest and following resistance exercise in men. J Physiol. 2012 Mar 25.
  3. Loenneke JP, Wilson JM, Manninen AH, Wray ME, Barnes JT, Pujol TJ. Quality protein intake is inversely related with abdominal fat. Nutr Metab (Lond). 2012 Jan 27;9(1):5.
  4. Moore DR, Robinson MJ, Fry JL, Tang JE, Glover EI, Wilkinson SB, Prior T, Tarnopolsky MA, Phillips SM. Ingested protein dose response of muscle and albumin protein synthesis after resistance exercise in young men. Am J Clin Nutr. 2009 Jan;89(1):161-8.