To brace or not to brace...the back/spine?

Here's where I get I little fuzzy on the idea of bracing.
Bracing is essentially a co-contracting of the "core" musculature correct? If that is true, in movement, especially of the spine, their must be an agonist/antogonist relationship between the contractors (shortening) and noncontractors (lengthening) muscles. In terms of athletics the spine moves. In the industrial setting where I work, we see the interspinalis muscles become (in my humble opinion) de-conditioned especially in transverse movement. As a result, we still deal with back pain even though their "core" muscles are strong as can be. I also don't know that I buy the idea that our spines only have so many
"flexes" in them before they break. The analogy used was that of a wire bending which will eventually break. Unlike a wire, the body has the potential to actually become better with use. So for me the search continues to find that balance between bracing (protecting the back) and moving (using the back) to perform functional activities in a wide variety of settings.