Meathead question here, Steve-O.
I'll admit that it might make me sound pretty stupid, but I was never able to find any real reads on it except a blurb or two here and there, and what I found was usually surrounded by that "bro-science."
So, I started weightlifting when I was young. At that point, when I trained, I thought I was training hard. As time went on, and I worked out with different people, and then college strength coaches, I learned what a real killer workout was, and how to push your body in ways your brain says are impossible.
When I started to take those sessions up to a higher level, after most sessions where I went balls out, I noticed something. An inflated sensation in my muscles, and an almost tingly feeling associated with it, and I felt good. I saw "Pumping Iron" for the first time a bit ago, where Arnold kinda describes what I am talking about, and calls it "the pump." I didn't want to necessarily use that term, 'cause calling it that makes me feel like a juicing frat boy that fake-tans.
I've read that the inflated sensation is from either increased bloodflow, or blood pooling, but it doesn't seem like I'd get any sort of good feeling from that, or why it's a boolean sort of thing. I never get a "kinda" pump. It's either there, or it is not.
Had a big push day last night, and had it happen, and I was askin those questions to myself, and decided to put 'em to the king of physiology.
most bankers tend to appreciate sweet smelling steve rather than fishy steve 