Well, I suppose it’s possible. I don’t know if it should be used for this purpose or not, but I can provide a theory behind why this MIGHT be possible.
Please keep in mind that I have not done any personal studies or research on the theory, it was just presented to me in a university lecture. So take it for what it’s worth. I am not advocating it.
At the base of the stomach, there is a pyloric sphincter, which regulates the rate at which food passes into the small intestine. Fluids exit the stomach more rapidly than solids, carbs more rapidly than proteins, and proteins more rapidly than fat. (This is the place where the reasoning of the trainer breaks down the most, because a whey PWO shake is liquid, so it will exit relatively quickly anyways)
Now, absorption of food and liquids by the stomach is, largey, negligible. Its main function is to break down the food (into chyme) which can then be easily absorbed by the small intestine. Carbonation is supposed to relax the pyloric sphincter, therefore getting food out of your stomach quicker, where it can be absorbed in the small intestine.
To make an anaology, it’s kind of like when people say that champagne “goes to their head”. What is really happening (supposedly at least) is that the carbonation (specifically the CO2) is allowing the alcohol to pass into the small intestine quicker, which means it’s absorbed faster. The result is you get drunk quicker. So the champagne doesn’t really go to your head, it goes to your small intestine.
The same theory applies to alka-seltzer or drinking a carbonated beverage if you just had a HUGE meal. It is supposed to allow the food to pass out of the stomach quicker, thus relieving indigestion.
There you have it. I’m not saying that that is necessarily 100% true. I think many of us can recognize that not everything professors say is always accurate, but I hope that has at least provided a theory as to why it MIGHT be true.
And again, with a whey PWO drink, since liquids enter the small intestine much quicker than solid foods anyways, it probably isn’t helping much. Sounds like he’s just trying to justify the Coca-Cola.