The nurse says, "yes, but..."
In order to ACCOMPLISH the air pressure one actually has a choice of using some accessory muscles more than others. One can direct the expansion up into the anterior chest, creating a big expansion there with minimal lateral and posterior thorax movement and minimal abdominal expansion - the way most people breathe when their doctor tells them to take a deep breath. Or, one can do the "abdominal breathing" I was taught in the dojo, being told "it's how babies naturelaly breathe": relaxing the chest and letting the abdomen expand with the inhale, deflate with the exhale. Or, one can focus on lateral and posterior expansion of the thorax, feeling very full and expansive while the chest is relatively quiet and the abdomen still.
(I actually had to show this to a nurse friend recently, with her hands on me, who thought I was nuts when I talked about different ways of breathing - because, indeed, reading texts will NOT teach you what you can actually feel and do as a living breathing being)
So reverse breathing, as I understand it, has to do with abdominal use - essentially contracting on inhale, expanding on exhale, yes? I may be wrong but that's what I think it is- somebody else will jump in and say if that's right or not....
I'm aware of abdominal breathing. I understand it to be primarily the diaphragm descending to draw the bottom (inferior aspects) of the lungs "downwards" (if you're standing), creating the necessary negative air pressure. Also aware of the different control of breathing by expanding the rib cage in various ways, and getting the "fullest" (not really a word) lungful by expanding the chest AND drawing the diaphragm down (abdominal breathing).
"Reverse Breathing" simply makes no sense to me. Do I "know" how the body works? That's hard to say - I've been "doing" aikido for about 17 years, raced competitive rowing for 3 years, judo for 8 years, and a professional rowing coach for nearly 30 years. I've trained rowing coaches, too, and some of the folks I've trained as coaches have (like me) developed young people so that they've gone on and won at world and Olympic championships. But I don't know anything about how the body works. I know that I don't know everything about how the body works. Reverse Breathing - if someone can show me what it is, perhaps, but what I've read here makes no sense.
Breathing in humans has mechanical, chemical, and neurological 'drivers' (you know that) and they've evolved pretty well - what we need to do is breathe without interfering with nature. Or perhaps learn to breathe taking advantage of some bits of knowledge - for example, does a brief Valsalva maneuver on exertion contribute to increased ppO2 in the lungs and better extraction of oxygen or not? Has such research been done either in CPR studies or sports lit? (I don't know).