Lately, I've heard of many coaches that are against the theory that the lumbar spine was designed to be stable and resist rotation, citing that if the lumbar spine wasn't meant to move that it would've been made with a solid bone instead of moving joints. Most of you know that this is my philosophy when it comes to training the lumbar spine. If you don't I'll reiterate them quickly. It should be strong and stable at all times. I don't like movement to ever come from the lumbar spine. Hip rotation, as well as thoracic spine rotation are what occur in athletic movements. Pure spine rotation rarely occurs, and in fact we generally don't want it to, and /or increase spinal rotation at least not on the lower back level.
The lumbar spine has very little in the way of rotation movement. Its total rotational degrees are around 13 from top to bottom according to Shirley Sahrmann. Each individual segment from has around 2 degrees of rotation. Individuals that aren't worried about lumbar spine movement should note that studies have shown disc problems begin to occur with as little as 3 degrees of rotation in the lumbar vertebrae. So while the lumbar spine does have some movement and rotation, we shouldn't be after increasing this motion whether on purpose or by accident. Rotation in the lumbar spine is a recipe for injuries, especially when combined with flexion. Where we do want motion is in the thoracic spine. I have posted several of my t-spine mobility exercises in previous posts that you can find by typing t-spine in the search on my blog.
Now this doesn't mean going the other direction and eliminating all rotational movements from training. These movements happen in virtually every sport. Just make sure all rotational movement should occur at the hips and thoracic spine. We should think of rotating at the level of the chest and shoulders, while locking the lower spine and abs into place.