Kick,
the blends I'm talknig about are blends that have the following;
Whey Protein Isolate
Micellar Casein
Egg Protein
maybe Soy Protein
Whey Protein Concemtrate
..usually they have added vitamins/minerals, extra BCAAs, and EFAs added to the mix.
BCAAs are important preworkout because they are present in the blood stream during your workout.
Since the body uses BCAAs from muscle tissue during intense workouts, by taking some before you use less body protein as fuel, and can stay anabolic during stress.
Essentially, you keep circlating levels of aminos in your bloodstream during the entire day, and before, during, and after your workout.
Studies have shown the anabolic and beneficial effects of adding BCAAs to your diet. I'm sure you know how anabolic the BCAA Leucine is. So it makes sense to have plenty of it available during your the time when you are sending the body it's most potent anabolic signals. Taking it pre workout gives the body the necessary nutirents to have an optimum workout environment inside your body and to spare your own body protein.
By maintaining circulating levels of aminos in your bloodstream you always have an anabolic environment and maintain what;s called Positive Nitrogen Balance. That just means you don'y cannabalize muscle tissue.
No point in working out hard and heavy for you to justy lose it due to not enough BCAAs. WHich in the ned are really the aminos most responsible for muscle hypertrophy.
That's why Whey Protein Isolate is so desired fo9r body builders.
UNfortunately, Isolate is digested extremely wucikly! And doesn't stay in the bloodstream for more than an hour or two. this means you have to ingest yor does of protein every two or so hours. Some people have no problem with that, but some do.
That's opart of the reason why the protein blends are popular now.
you can have a protein shake, and whole foods, and maintain higher levels of circulating amionos.
Thas is the key.