Pre Workout Protein Supplementation 101: Slow or Fast, Bolus or Pulse? Protein Synthetic Response is Identical!

Should she drink her protein shake all at once or in 33ml gulps every 15min, if she has it before her workout? And wait, wouldn't it be better to have the shake afterwards, anyway? A recent study provides some answers.

I don't know if you notices, but it has been a while since the last study from the Exercise Metabolism Research Group at the Department of Kinesiology of the McMaster University in Hamilton, Ontario, Canada, hit the SuppVersity news. Allegedly, I mentioned Stuart Phillips only a couple of days ago, when I referenced the West study on "Associations of exercise-induced hormone profiles and gains in strength" (West. 2013), in the context of the questionable significance of post-exercise increases in testosterone levels, as far as muscle and strength gains are concerned - for those who missed that, it was  in the "Anabolic Workouts Revisited" post from last Monday. That was however about it as far as the news of the last weeks are concerned. So I was already wondering, when the first of you would be showing initial signs of "acute protein synthesis in response to protein ingestion study withdrawal symptoms", when I hit onto the latest study Phillips' group at McMasters participated in. The lead author of the study is however Louise M. Burke who's currently working at the Australian Institute of Sport in Canberra, Australia.

What happens if you ingest your post-workout protein before the workout ;-) ?

The aim of the study, of which the authors explicitly state that it is a quasi-followup to previous results which have conclusively identified fast acting protein sources (mostly whey, in some instances EAAs) as superior triggers, or I should say, promoters of post-exercise protein synthesis, was

"[...] to investigate the effects of manipulating patterns of aminoacidemia from protein sources consumed before a bout of resistance exercise bout." (Burke. 2013)

To this end, Burke et al. simulated the ingestion of slow or fast protein sources by bolus vs. pulse feeding of a leucine-enriched (+5g) whey protein drink (Nestec by Nestlé, sponsor of the study; the reason for the enrichment was to make sure that there would be a decent amount of leucine in each pulse serving).

• Bolus (B) - 1 x 500ml w/ 25g whey + 5g leucine drink, 14 x 33ml placebo every 15 min
• Pulse (P) - 1 x 500ml placebo drink,  14 x 33ml w/ 1.79g whey + 0.36g leucine each
• Placebo - 1 x 500ml placebo drink, 14 x 33ml placebo drink

The subjects, 12 resistance-trained men (age: 27y; body mass: 94.3kg; 1 RM single leg ext.: 42.8kg) with greater than 2 yr of experience of regular (at least twice per week) strength training, who had followed a standardized diet before each of the testing sessions (energy content of 80kcal/kg BM; 45%/34%/21% of the energy from carbs/fats/protein), started consuming their large 500ml beverage and the subsequent 14 small 33ml servings (every 15 min) 45min before they performed a standardized leg training session:

"This bout consisted of a  standardized warm-up, followed by 10 sets of 8–10 repetitions of leg extension at a workload equivalent to 80% of the specific leg 1 RM with 2-min recovery between sets. The leg that performed exercise was alternated for each trial. The duration of the resistance bout was approximately 45 min." (Burke. 2013)

Before during and after the exercise bout blood samples were collected. Muscle biopsies from the vastus lateralis of the exercised leg were taken 45min before, as well as after 1 h and 5 h of recovery.

Figure 1: Serum leucine and insulin levels after bolus and pulse ingestion, expressed relative to placebo group (left) and fractional protein synthesis rate (in %/h) during the 5h following the rest period after the workout (right; based on Burke. 2013)

As you can see in figure 1 the results basically confirmed the scientists expectation that the provision of protein before a workout would work just as well, because - more than anything else - it is the availability (or should I say abundance?) of amino acids in the blood stream that is the main determined of post the actual fractional protein synthesis rate (FSR) after moderate  volume workout like the one the participants conducted in the study at hand. In addition it did, at least as far as the protein synthetic response goes, neither make a significant difference, whether the subjects had all their protion at once before the workout or consumed it in 15min intervals before and during the workout.

Bolus or pulse = fast or slow? Pulsed whey does not equal casein (imho)

What I am personally not happy with, though, is the way Burke et al. equate the "pulse" protocol to the ingestion of a "slow" protein source, such as a micellar casein protein, for example. While they put that into perspective in the discussion of the results (see below) and despite the fact that do see the rationale of Burke et al. not to use a real slow digesting protein like casein in order to have absolutely identical amino acid compositions and to exclude other confounding factors, it is at least in my humble opinion somewhat confusing for the "average" reader. And while it is likely that the results for a "real" slow digesting protein would be similar, this would warrant direct experimental evidence. A fact the authors only hint at indirectly towards the end of the discussion of their results, when they state:

"[...] A specific issue in interpreting the finding of these previous studies and in increasing the utility of the concept of ‘‘fast’’ and ‘‘slow’’ dietary proteins is the difficulty of determining the individual and interactive contributions of the different AA composition of protein-rich foods and the digestibility of proteins or protein-rich meals to the pattern of delivery of these AAs. Our protocol, in which the same (fast) protein was consumed to achieve its traditional AA profile or as a series of small divided feed-ings to replicate the plasma leucine response associated with a slow protein, provides an opportunity to differ-entiate these effects." (Burke. 2013)

But hey, who knows, maybe that's going to be the research question of the next paper... and in the mean time it will spare you to buy two or even more different protein powders ;-)

"So what's better Dr. Andro? Pre- or post-workout protein supplementation?"

I guess most of you won't care anyways, as there is another question that's now preying on your minds... but to be honest, I can't provide you with a definite answer to it (see headline). What I can do, however is compare the study by West et al. (West. 2011) which used 25g of whey protein post workout to the one at hand (Burke. 2013).

Figure 2: Fractional protein synthesis (FSR in %/h) after the workout with post workout protein ingestion (West. 2011) and pre workout protein ingestion (Burke. 2013) on the left; relative increase in FSR in the two trials (compared to fasted for West. 2011 vs. Placebo for Burke. 2013) on the right (please mind that this is by no means a scientifically valid comparison, it's more of a "food for thought illustration"!)

I've done just that for you in figure 2, and what this comparison tells you is that it does not make a difference, whether you ingest all your protein as a bolus after a workout or start "pulse ingesting" (mind my words in the previous paragraph wrt to "slow != pulse") your protein 45min before the workout - at least, if you take the relative increase in fractional protein synthesis as a measure (figure 2, right). 

Unfortunately, both the composition of the protein supplement (25g whey in West. 2011 vs. 25g whey + 5g leucine in Burke. 2013), as well as the exact outcome variables that were measured (1-3h and 3-5h FSR in West. 2011 vs. 5h post workout FSR in Burke. 2013) were different, so that the comparison of the relative increases in protein synthesis I plotted on the right hand side of figure 2 is actually not 100% valid.

Moreover, and this is something I know a couple of you will now be thinking of, this comparison does by no means allow for any quantitative predictions with respect to the question of ...

What would happen, when you do both: Pulse ingest before and bolus ingest afterwards?

If  you don't remember or - even worse ! - have not read the previous SuppVersity post "Protein Synthesis Beyond the '20g Limit': Study Shows Exercise Facilitates 32% Greater Increases in Fractional Protein Synthesis With 40g Instead of 20g of Whey PWO" click on the image and (re-)read it ;-)

In view of the fact that the existence of a "threshold level" of protein intake, where the addition of even more protein won't yield any further benefits appears to be self-evident, the exact amount of this limit has yet still to be determined. At least after a workout, it seems that this threshold would be higher than the 25g and 20g of protein the subjects ingested in the Burke and West studies, respectively (please read my previous post "Protein Synthesis Beyond the 20g Limit" for a more detailed discussion of this topic).

That being said, it is reasonable to assume, but would likewise warrant experimental verification, that the combination of both protocols could increase the fractional protein synthesis even further. Yet while I am 100% sure that they won't simply add up, I would hesitate to bet money that the difference would actually reach statistical significant... at least with a low volume leg extension workout as it was used in the studies at hand.

References:

• Burke LM, Hawley JA, Ross ML, Moore DR, Phillips SM, Slater GR, Stellingwerff T, Tipton KD, Garnham AP, Coffey VG. Preexercise aminoacidemia and muscle protein synthesis after resistance exercise. Med Sci Sports Exerc. 2013 Oct;44(10):1968-77.
• West DW, Burd NA, Coffey VG, et al. Rapid aminoacidemia enhances protein synthesis and anabolic intramuscular signal-ling responses after resistance exercise. Am J Clin Nutr. 2011; 94:795–803. 
• West DW, Phillips SM. Associations of exercise-induced hormone profiles and gains in strength and hypertrophy in a large cohort after weight training. Eur J Appl Physiol. 2013 Jul;112(7):2693-702.  

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. 2013). 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. 2013)

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. 2013)

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. 2013)

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 (dormtainment.com): 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. 2013).

References:

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. 2013 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. 2013 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). 2013 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.