Post-Workout Protein Supplementation: Speed & Source Don't Matter for Real-World Size & Strength Gains - Really?

On a side note: An adequate protein intake is as important for men as it is for women, but both can - for few with real effort - achieve adequate protein intakes from their diet alone - with the same muscle-building effects.

If you believed only 50% of the claims on the boxes of the currently available protein supplements, you'd have to have at least five products from three different brands to see optimal results. Luckily, there's science to tell you that the only thing you need is a cheap high EAA protein source that doesn't give you gas, the runs or other side effects...

Well, that's at least what a cursory analysis of the results of two new studies suggests. Together, they can be used to argue quite convincingly that neither the protein source (beef, chicken or whey | Sharp 2017), nor the ratio of fast (whey) vs. slow (casein) proteins (Fabre 2017) will have a meaningful effect on the only relevant study outcome: your real-world gains.
Initially, you'd have to tell people to forget all studies that measure only fractional protein synthesis rates, do not even look at studies that measure only mTOR and related protein expressions (which is not totally wrong, because eventually neither mTOR nor FPS rates have been shown to reliably predict long-term gains). As soon as you've done that the evidence base they can use to argue against is reduced by at least 95%. The only thing that's still left for you to do then, is to reference the latest paper by Sharp et al. (2017) and Fabre et al. (2017) to argue that...

• it doesn't matter if you consume a beef protein isolate (Beef), hydrolyzed chicken protein (Chx) or whey protein concentrate (WPC) post-workout (Sharp 2017), 
• it makes no difference if you use whey protein alone or "prolong its effects" by adding casein at different ratios (1:0, 1:1, 1:4 whey-to-casein ratio | Fabre 2017)

If you still look at incredulous faces, do what I'd do. Show them what Sharp et al. and Fabre et al. observed in their most recent double-blind resistance training studies with previously trained subjects, when they had them take

• a 46g bolus of either WPC, Chx, Beef, or Maltodextrin post workout before leaving the laboratory and  at similar times on non-workout days (Sharp 2017), or
• a 20g bolus of whey or a mix of whey and casein at 10 g of whey protein to 10 g of casein or only 4 g of whey protein to 16 g of casein protein (Fabre 2017), respectively. 

in form of original graphs from the study. Emphasize that, as everyone would expect it, the dietary and training regimen were standardized in both studies to isolate the effect of supplementation on the muscle responses to resistance training. And voila!

Figure 1: Changes in lean and fat mass over the course of the study period in Sharp 2017 (top) and Fabre 2017 (bottom).

You will have convinced most of your readers that neither (a) the source of protein, or (b) the ratio of fast to slow digesting protein would matter. I mean, there's no inter-group differences in either, the lean mass and fat mass data from the Sharp (Figure 1, blue) or the Fabre study (Figure 1, orange)? What? Oh, yes, obviously that's with the exception of the maltodextrin control in Sharp et al. (2017) - but everyone knows that "carbohydrates are the devil", no?

(Un)fortunately, science is more complicated than that...

Ok, that was what you may be reading elsewhere, but not here, where, much to the frustration of friends of stupifying black-and-white answers, there's always an "on the other hand". I mean, I know that it would be nice if we could take a brief look at two studies, only, to determine (ideally "once and for all") if the source and absorption kinetics of your post-workout protein supplements matter. This, however, would mean that we ignore previous evidence that puts the results of Sharp's and Fabre's study into perspective and saves us from overestimating their significance:

• Figure 2: Changes in lean and fat mass over the course of a 10-week training study comparing the effects of PWO supplementation of carbohydrate control (P) to whey + glutamine + BCAA (WBG) and whey + casein (WC | Kerksick. 2006).

  Back in 2015, I discussed at length, how the superior improvements in lean and fat mass with a combination of whey and casein, Kerksick et al. (2006) observed over the course of a 10-week study comparing a combination of 40 g per day of whey protein + 8 g per day of casein (WC), or  40 g per day of whey protein + 3 g per day branched-chain amino acids + 5 g L-glutamine (WBG), clearly demonstrate that it makes sense to combine fast and slow digesting proteins to augment the body composition changes in resistance-trained men over those you'd see with a purportedly more anabolic mix of whey + amino acids.
  
  This study doesn't only refute the claim that "advanced proteins" that have been spiked with BCAAs and glutamine would yield optimal gains, it also highlights that, as soon as the total supplemental protein intake post-workout is high enough to exceed what can be used for protein synthesis, almost directly [with 48g/serving that's certainly the case, with 20g/serving as they were used in Sharp et al. (2017), it's almost certainly not the case], there clearly is a benefit of the addition of slow-digesting casein protein to sustain the muscle-anabolic state of postprandial hyperaminoacidemia.

• I have also discussed the results of studies by Churchward‐Venne et al. (2012) and Koopman et al. (2008) in various previous articles about protein supplementation, because they highlight the relevance of threshold doses of leucine (Koopmann 2012) and essential amino acids, in general (Curchward-Venne 2012).
  
  Wouldn't that imply that the protein source should matter? Yes, it does and that's also the case in studies comparing low(er) dosages of protein supplements than Sharp et al. (2017) who achieved threshold doses of all relevant amino acids with their whopping 46g of protein from various protein sources. In addition to that, the protein sources The dosage is yet not the only difference to more practical comparisons such as whey protein vs. steak or whey protein vs. chicken breast... why's that? Well, by comparing whey protein concentrate to isolated beef protein and hydrolyzed chicken protein, all three proteins were rapidly digesting.

References:

• Churchward‐Venne, Tyler A., et al. "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." The Journal of physiology 590.11 (2012): 2751-2765.
• Fabre, et al. "Effects of Post-Exercise Protein Intake on Muscle Mass and Strength During Resistance Training: is There an Optimal Ratio Between Fast and Slow Proteins?" Int J Sport Nutr Exerc Metab. 2017 Apr 19:1-23. doi: 10.1123/ijsnem.2016-0333. [Epub ahead of print].
• Kerksick, Chad M., et al. "The effects of protein and amino acid supplementation on performance and training adaptations during ten weeks of resistance training." The Journal of Strength & Conditioning Research 20.3 (2006): 643-653.
• Koopman, René, et al. "Co-ingestion of leucine with protein does not further augment post-exercise muscle protein synthesis rates in elderly men." British journal of nutrition 99.03 (2008): 571-580.
• Phillips, Stuart M. "A comparison of whey to caseinate." American Journal of Physiology-Endocrinology and Metabolism 300.3 (2011): E610-E610.
• Sharp, et al. "The Effects of Beef, Chicken, or Whey Protein Post-Workout on Body Composition and Muscle Performance." J Strength Cond Res. 2017 Apr 7. doi: 10.1519/JSC.0000000000001936. [Epub ahead of print]