Based on the research of the past few years, almost all clinics in the US have been rehabilitating the low back all wrong.  Why?  In order to stabilize the spine, you must recondition the small muscles close to the spine called the multifidus and the deepest stomach muscle called the tranversus abdominus.  However, almost all rehab programs for the back have focused on the large muscles on the outside that help extend and bend the back, not the muscles responsible for stability.  In addition, these same programs have focused on the large stomach muscles while neglecting the muscle responsible for stabilizing the spine.  

As a result of this incorrect focus, many people have gotten worse with exercise for low back pain.  It's become so common, that new medical and psychological terms and diagnoses have been dreamed up to try to explain why so many people do so poorly.  However, the segmental approach to low back rehabilitation is based on dozens of medical research studies showing that focusing on the right muscles works!

To demonstrate the problem and the solution, lets say you stacked a bunch of kids blocks one on top of the other.  As you might imagine, they wouldn't be that stable.  Any small amount of force would easily knock them over.  Put your mouse over the blocks now.  As you can see, even the slightest pressure from your pointer topples the blocks.  This is like a low back with weak muscles.

Now lets say you shore up the blocks with wires.  Since the wires don't connect each block to the other, the blocks still aren't stable.  Go ahead, knock them over with your mouse again!  The wires are like the big muscles in the back, they aren't good at stabilizing the spine.  Since this is what is strengthened in rehab programs, the low back never becomes stable and stays painful.

Finally, you learn from your mistakes and tape the blocks together.  Now they're stable as they have a connection that goes from block to block.  This is exactly what the segmental muscles such as multifidus do in your back, they hold the bones together by going from bone to bone.  Now try to knock them over!