A number of feeding approaches have been thrown around when it comes to taking your protein.  Most research studies and most gym-goers deliver the entire dose of protein and/or amino acids in one fast dose.  Another approach, rarely used in everyday life, is to sip on the protein shake over the course of several hours.  I’ll admit, I myself, have advocated the use of this second approach, based off of available science, but considering some recent evidence I may alter my stance.  For starters, remember that several research studies have shown that when a dose of protein is given, rapid increases in blood concentrations of amino acids occur within about 30 – 45 minutes of ingestion and remain elevated above baseline levels for around two to three hours.  Add to this the fact that increased levels of amino acids levels outside the muscle cell as opposed to the levels inside it stimulate increases in muscle protein synthesis.  Thus, it makes sense to suggest to people to deliver a small dose of amino acids on a regular basis over an extended period of time because it will maintain an increased level of amino acids in the blood for availability to the muscle cell to use for protein growth.

An excellent research study around ten years ago examined the changes in whole-body protein synthesis after having people ingest a single dose of whey protein or repeated doses over an extended period of time and found exactly what you would think.  Amino acid and protein turnover levels remained elevated over a longer period when repeated doses were taken, but sharper increases in protein growth were found when a large, single dose was used [1].  Fast forward to present day and a recent study was recently published in the American Journal of Clinical Nutrition that used more specific techniques to compare the changes in MUSCLE protein synthesis (not whole-body protein synthesis) after a single 25-gram dose of whey protein or ten repeated 2.5 gram doses every 20 minutes over a three hour period [2].  An additional benefit to this latest study was that it compared the two supplementation approaches after a typical bout of lower body exercise; a nice touch considering the previous study did not incorporate any exercise.

Surprisingly, a somewhat different picture emerged.  For starters and as expected, both forms of amino acid administration increased the concentration of essential amino acids in the blood, a critical factor regarding muscle growth.  But when given in a single dose, amino acids levels increased by 162% one hour after exercise.  When repeated doses were given the increase was 53%.  Providing multiple doses did prolong the increase in amino acid levels and in fact amino acid levels were significantly greater two hours post-exercise after repeated doses were provided.  On the other hand, simply increasing essential amino acid levels only tells part of the picture and when measures of muscle protein synthesis were made, a single 25 gram ingestion of whey protein increased protein growth to a significantly greater extent when compared to repeated doses both early (1 – 3 hours) and later (3 – 5 hours) after the exercise bout.  It is this last finding that the authors felt was the most telling.  A highly specific measurement technique was utilized that singles out muscle protein growth from other forms of protein and upon utilizing this technique, the authors concluded that a single dose resulted in greater stimulation of muscle protein growth.

In conclusion, a number of take-home points should be made.  For starters, taking your protein in one or repeated doses does a good job of increasing amino acids levels in the blood as well as increasing rates of muscle protein growth.  In short, either method appears to be effective and if you like sipping on a protein shake throughout the day don’t let this article sway you from doing so.  The results, however, do suggest that a more favorable outcome may occur after ingesting your protein as a single dose resulting in higher levels of muscle protein growth when compared to multiple doses [2].  Fortunately, most people I know mix up their post-workout shake and get it in them as fast as they can and a recent study suggests that this approach is indeed very effective at increasing amino acid levels which goes on to also stimulate positive increases in the growth of muscle proteins.

REFERENCES

1. Dangin, M, et al. The digestion rate of protein is an independent regulating factor of postprandial protein retention. 2001. 280(2): p. E340-8.
2. West, DW, et al. Rapid aminoacidemia enhances myofibrillar protein synthesis and anabolic intramuscular signaling responses after resistance exercise. Am J Clin Nutr, 2011. 94(3): p. 795-803.