Core has become a buzz word, but most people don’t really know what we mean by core.    I have heard many people say, “I have a weak back.  I need to work my core.”  They are right, but usually when they say this they signal to their abs.   Everyone seems to interchange the words “core” and “abs.”  But in Pilates when we refer to the core, we are talking about more than just your abs. 
Your abs are part of your core, but so is your back, your butt and your shoulder girdle.  Basically, your entire trunk is part of the core.  A bad back might get better by strengthen the abs, but not if your back problems come from abs that are too short already.  You need to work every part of your core, together—as if all the muscles that make up your trunk are a team working together to keep you out of pain.   You need to learn to stabilize and hold part of your core (like your pelvis) still while you move other parts (like your ribs).    Sadly, working the core isn’t as simple as doing a few crunches.  And just doing ab-work alone usually isn’t enough to fix back problems.
Your core, when worked as a unit can help give you deep strength inside the body.  And working the core properly can help reduce pain not only in the back, but in the neck and shoulders, too.