Copyright: fotomircea / 123RF Stock Photo
Currently, one of the leading theories behind muscle growth is the stimulation of protein synthesis frequently, a process in which new contractile components and proteins are generated in response to resistance training. It's thought that when stimulated multiple times over a long period of time that this leads to muscle growth.
Thus, the purpose of this study was to observe if periodic bolus' (large amounts in a single serving) of protein is more optimal for stimulating protein synthesis than many small "pulses" of protein for stimulating this muscle building process.
Why Study This
This is actually quite important for a few reasons.
1. Many people eat small meals throughout the day in hopes of "stoking the metabolic fire" (which isn't true, btw). If a bolus of protein is more optimal, this may force those individuals to rethink their position.
2. Many people like myself practice intermittent fasting which incorporates fewer, larger doses of all ingredients. These findings may have implications for the person using this style of dieting.
3. This may provide insight into the best methods for consuming protein if your goal is to improve muscle mass. If bigger meals are more appropriate and you currently eat many small meals, the findings may required you to switch your methodology.
Eight, recreationally active young males were recruited for this study. Participants underwent a 10 repetition maximum test of bilateral leg extension to determine weight amounts for the upcoming study. This preliminary test was run 1 week prior.
Prior to beginning the resistance training protocol, the subjects were injected with what is known as a phenylalanine tracer. Phenylalanine is an amino acid and researchers can trace this amino acid by taking muscle biopsies, where they literally remove part of the muscle and study it. Observing the amount of phenylalanine that has been absorbed (or not absorbed, is a good indicator of this amino acid being incorporated into new muscle tissue (1).
Afterwards, subjects were exposed to a resistance training protocol consisting of 8 sets of 8-10 repetitions, using their previously defined 10 RM weight (taken a week prior), using 2 minutes of rest in between sets. A fairly typical procedure for testing protein synthesis changes.
The image above displays when biopsies and blood samples were taken from the subjects in group 1 (bolus). The asterisks [ * ] indicate when blood was drawn (Immediately after training, 4 times per hour until the 3rd hour and then once at 5 hours post). Muscle biopsies [ upward arrows ] indicate when muscle biopsies were taken.
The Protein Procedures
This study was a crossover design, meaning that the participants were involved in both procedures, separated by 30 days. This type of gap is typical for a crossover design.
Trial 1: Upon completion of the resistance training protocol, subjects were provided with a single bolus dose of whey protein of 25 grams. Typically, this is the amount of protein that would be suggested normally. Upon completion of drinking the whey, all other measurements (image above) were taken for the duration of the trial.
Trail 2: Upon completion of the resistance training protocol, subjects were provided with 10, 2.5 gram doses of whey (equalling 25 grams total), every 20 minutes until the 25 gram mark was reached. During this time, blood draws and biopsies were the same as trial 1. The only difference however, was that no per-workout biopsy was taken during trial 2.
Whey May Act Differently Than Normal Proteins
It's important to remember that even though it took 60 minutes for the whey to really enter the bloodstream in the form of amino acids, this is extremely fast, and much faster than that of normal protein, from say, steak or chicken.
Even though steak or chicken will provide a large dose of protein, the digestion rate of that type of protein is much slower than that of whey. So essentially, even taking in 25 grams at a single time, the rate of amino acids entering the bloodstream will look more like that of pulse dosages. Just because it was all consumed at once doesn't mean all will enter the bloodstream at the same time.
It's possible that this significant increase of amino acids in the blood and of course the drastic rise in protein synthesis observed with whey, would not be the same with regular proteins.
Whether or not that's actually relevant long term remains to be determined. If you want immediate protein synthesis as revealed in this study, I suggest consuming whey close to the workout and then following up with normal proteins about 2-3 hours after drinking whey (since it will take some time for the amino acids from normal proteins to breakdown and actually reach the bloodstream).
This is also one of the arguments against using casein, since the entrance of amino acids into the bloodstream is slower. Again, whether that matters long term remains to be determined.
Acute Increases In Protein Synthesis Aren't Necessarily Important
It's really difficult to say if this immediate increase of protein synthesis is actually relevant, long term. Long term muscle growth is of course more associated with long term, consistent increases of protein synthesis, so it's difficult to know if a difference of a few hours is meaningful.
However, consider the images above, with how quickly protein synthesis rises and further, how much high protein synthesis is at the 3 hour mark, compared to the PULSE doses.
Over time, these extra 3 hours could really stack up. Over 6 workouts, that's potentially 18 hours MORE of increased protein synthesis. Over the course of a year, that could equate to 1008 hours EXTRA protein synthesis. That in my opinion could be significant.
Further, as displayed in the graph above, the rate of protein synthesis at the 3-5 hour mark was much higher for BOLUS than PULSE. Who's to say that that increase wouldn't continue or if the PULSE dose even reaches the same level. Surely more research is required but based on these findings, It makes sense to consume a fairly fast digesting protein around the workout, followed by a full protein source later on, like steak or chicken.
Protein AROUND The Workout
It's important to note that this doesn't mean that you need to consume your protein only immediately after training, but rather sometime around the training session.
Personally, I prefer having protein before a workout. Considering that it takes probably 40-70 minutes for the amino acids to actually hit your bloodstream, those amino acids should be reaching the bloodstream close to the end of your workout, which is a prime opportunity for growth.
While the anabolic window per se isn't very important (if total protein intake is high), increased anabolism does exist after training, so supplying the muscle with amino acids during that time is certainly appropriate.
The Anabolic Window
The anabolic window, or the time just after training is a fairly controversial subject. Alan Aragon and Brad Schoenfeld recently indicated that the post workout window isn't as important as previously thought (3).
Essentially, consuming protein immediately after the workout is not as big of a deal if total protein throughout the day is adequate. For example, if 2 people consumed the same amount of protein, yet one consumed evenly through the day and the other consumed most of their protein after training, there probably wouldn't be a huge difference.
However, it's important to note that after training, you are certainly in a more optimal position for growth, so it makes sense to try and take advantage of it. It's just that you won't lose gains if you don't consume protein immediately. Either way, it's still strongly advised that you consume adequate protein both in total and around the workout.
Based on these findings, if you're chasing an optimal increase of protein synthesis around the workout, it's probably best for you to consume that protein in a full dose, around 20-40 grams of protein, rather than smaller ones. Further, it's important to remember that this was whey and the responses observed in this study may be drastically different when compared to a normal protein source like steak or chicken.
For an optimal response, I suggest having a bolus of whey either before, after or before and after resistance training, with a follow up meal a few hours afterwards.
Additionally, as mentioned in a recent article about protein synthesis and milk, it may be in your best interest to make sure you mix that whey with a fat and carb source, such as whole milk, for a maximum response.
Why This Should Matter To You
It matters because it provides information on the optimal ways to stimulate processes, which are thought to be drivers of muscle growth. By knowing that a BOLUS of protein is more optimal than PULSES, you can begin to mold your dieting approaches around this information for the result you desire.