Click on this link
http://www.nytimes.com/2009/06/21/magazine/21FOB-physed-t.html?emc=tnt&tntemail1=y
Hey, I can’t write this any better myself. It talks about more contemporary thinking in core stability training with the legendary Stu McGill, PhD. It is worth reading and then viewing the video show McGill going through the propper way to crunch etc.
Make sure to add exercise as a preventative measure as well. Like the bird dog:
http://chiropractorny.com/2011/03/15/back-pain-exercise-the-bird-dog/