Aww geeze, I knew someone was going to ask some followup questions and I'd be out of my depth!
To be honest, I didn't practice in the field very long as an RT because I fell into hospital IT after my rotations and took to it like a duck to water and ended up really enjoying that as a career.
I'm gonna refer you to this study which - you are right- does show the insp/exp trainers help to strengthen breathing muscles. So perhaps it's the equivalent of using weights at the gym vs just doing diaphragm breathing exercises.
To be honest, I didn't practice in the field very long as an RT because I fell into hospital IT after my rotations and took to it like a duck to water and ended up really enjoying that as a career.
I'm gonna refer you to this study which - you are right- does show the insp/exp trainers help to strengthen breathing muscles. So perhaps it's the equivalent of using weights at the gym vs just doing diaphragm breathing exercises.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4316503/