You told me nothing new, I meant abs and lower back as a generalisation, I still think its a bunch of bullshit, deads and some crunches are all these "core" people need, are you a PT?Do you have 12inch arms and a certificate?
I told you the anatomical fact. That obviously is new to you since you refer to the core as the abs.
I have 19 inch arms and sub %10 bodyfat I own a gym and make a lot of money training people and have done so for the past 14 years Unlike you, I'm educated how the body works and I make a very good living helping others as opposed to sitting in my parents house hogging their computer and raving about how I don't understand the basics
Deads and crunches are fine. Even great. The point is, the better core stability you have, the better you'll perform these other exercises and the more benefits you'll reap from them.
In case you're curious, you don't need an ab ball or specialized "gay" equip in order to strengthen the core. That works, but people don't have the time and patience when what they really want is visible results. What also is effective, however, is doing the exercises correctly over and over and supplementing with a little direct core action. That's plenty for most people.