Ok, so long as you understand it is not just a mental edge that is obtained. To say that people who spend their money and consume these intra workouts are just gaining a mental edge and nothing else is a bit ignorant.
Can you demonstrate that a trainee with adequate pre and post-wo nutrition gets a damn thing from all this crap? I know you can't do so with research because it doesn't exist.
And any bb'er you can name who claims to benefit from this stuff... Well, I could come up with ten counterexamples who are better on stage and don't waste their money on this shit.
Also, it is ass-backwards from a science perspective. I respect JM a great deal, but his ditch-digging analogy with how this stuff works is terribly misguided. The primary breakdown pathway in skeletal muscle activated by resistance training is the ubiquitin-proteasome system which:
A. Is not significantly suppressed by either insulin - even at supraphysiological levels - or carbohydrate ingestion.
B. Even if you could suppress it you wouldn't want to because it is the driver for tissue remodeling. You would essentially be preserving damaged myofibrils in favor of having them repaired.
Insulin does suppress lysosomal proteolysis, but this is a minor player and is suppressed at very low serum insulin levels. Doubling basal insulin essentially caps out suppression of proteolysis and that can be achieved without carbs at all - much less shit that costs more $/gm than test.
Glycogen depletion is also not a concern for the majority of resistance trainees, but even in those few where marathon workouts and carb restriction might be issues it still just requires adequate daily carb intake to replenish - no magic shakes necessary.
There is just zero fucking evidence this shit does any good for a non-fasted trainee. But, if it is working for you then keep at it, just don't insist that those of us who don't see a benefit are ignorant. I used IW shakes for years, then quit and noticed no difference - which is in line with both the science and the experiences of many others.