Physiological Properties and Effects:
Whey Protein Isolate (WPI):
Whey protein isolate (WPI) was said above to be the king of proteins, but what does that mean? Why are proteins in general necessary, and more importantly, what are their functions as a workout supplement?
When you vigorously train or exert yourself, a process called protein degradation (the breakdown of muscle protein) begins so that the body can fuel itself. Think of this like shutting off your engine, in order to fuel your car (muscle protein breakdown). As this entire process plays out, the available pool of amino acids in skeletal muscle depletes, as they too, are drawn in and broken down in the natural, catabolic process during exercise training.
While this situation is quite adequate during a training session, it’s precisely the opposite of what we want afterwards. At that point, we want the available pool of amino acids to increase, protein degradation to slow or stop, and muscle protein synthesis to increase. The famous, “anabolic window” is occurring during this time period, so a protein powder that is rapidly digested, and that rapidly increases the available pool of amino acids, is needed to ensure that the switch between protein degradation to synthesis is as beneficial as possible. After this anabolic window passes, or before it even begins, we also want to ensure that the available pool of amino acids is high enough for your body’s constant growth cycle.
At this period, protein quality is also vital. Human skeletal muscle makes the most use out of a few, particular amino acids, and so a quality protein needs to have an amino acid profile that is optimal for this context. An, “optimal amino acid profile” contains a high amount of BCAAs, and in particular leucine, to counteract the rate of leucine oxidation that occurs as the fractional rate of protein synthesis decreases, and the rate of muscle protein degradation increases.
We chose whey protein isolate as the only protein in Core ISO for precisely these reasons. An excess amount in the available pool of amino acids (especially leucine) is called hyperaminoacidaemia, or specifically to leucine, leucinaemia. After a period of intense exercise training, we want this condition to arise immediately, peak after approximately one hour, and then be sustained until another protein source can be ingested. The evidence is quite clear that whey protein isolate not only achieves this, but also may achieve it at a greater potency as compared to other protein sources.
In a non-double blind study, two groups of healthy men received either micellar casein, or whey protein isolate, after a sustained bout of exercise training. Post-training, muscle protein synthesis, essential amino acid, and leucine levels were tested and compared. The study authors conclude that, “the ingestion of isolated whey protein supports greater rates of MPS than micellar casein both at rest and after resistance exercise in healthy elderly men. This result is probably related to a greater hyperaminoacidaemia or leucinaemia with whey ingestion.”
As we said above, it is critical for a protein’s effectiveness that it contain a robust amino acid profile, one that is particular high in leucine. This is because leucine is both the most physiologically important amino acid, with respect to muscle mass, and the most extensively studied. Data on leucine demonstrate this amino acid plays critical roles in stimulating skeletal muscle protein synthesis, and ribosomal biogenesis and assembly (the literal building of muscle tissue), along with playing a lesser role in insulin signaling and gluconeogenic processes. As a result of these diverse roles, leucine has been demonstrated to significantly stimulate skeletal muscle protein synthesis, and attenuate protein degradation, as in the above study, by both insulin-mediated and non-insulin mediated mechanisms.
In order to counteract a negative intramuscular protein balance, a number of things need to occur – mostly, a rapid increase in the availability of amino acids. There is strong evidence to suggest that, amongst protein supplement, WPI best achieves this feat.