Also want to question this definition of reflexive ab (I'm with the commenter above...there is something undignified about the word "core") stability:
“In sum, reflexive core activation is done by assuming any developmental position with joints centered, while maintaining diaphragmatic breathing with or without an outside stimulus or a part of the body creating a perturbation.”
Here's how I think of the reflexive property, let me know what I'm missing:
This winter I shoveled a lot of heavy snow. My abs kicked in to protect my lower back with each miserable "rep."
That's how I think of the reflexivity of the abs. It has little to do with breathing, more about muscle contraction for a purpose: to protect the lower back. I guess if you're chest breathing this might get messed up like everything else in your life will.
KBs, DLing, L-Sits,front levers, dead bugs, crawling like a baby, etc. (assuming good form) are different ways of getting this important protective mechanism.