In the attached video we look at my daughter who has a lot of spine extension and when she extends this leads to a “hinge” in her lower back. What is often advocated during spine extension is a gentle and gradual “rounding” that is equal at each segment.
It is assumed that if you have a “hinge” you are moving “too much” at that spot and this could increase your injury risk. Therefore, “hinging” is a suggested to be a movement flaw.
Why this isn’t an inherent movement flaw
It is an assumption that each motion segment should have the same range of motion. If we argue that hinging is faulty it assumes that at that segment the motion is at a greater percentage of its maximum and is undergoing greater loads. But we can’t say that. The hinged region might be only moving at 80% of it maximal range while other segments are moving at 90% of their range. We see differences in the range of motion at each joint. Even side to side.
When might this be detrimental to performance?
I’m not arguing that it always good to use this much spinal extension range of motion. There are tasks that are better performed with less. That is seen in the video where I drop violet on her head. When she does a back handspring she wants to immediately arch her back and almost have her hands land where her feet were. So she uses her ability (i.e. lots of spine extension) to get backwards rather than jumping backwards and doing a handspring with much less arch. For a nice take by a gymnastics coach here is a short article
What might be more important for injury or pain
The total volume of back bending and always doing it the same way might be more a risk than the actual quality or technique of movement. If you arch your back in the same way, during all activities you might exceed your ability to tolerate the motion. This is regardless of how you arch. Its just a volume issue.
If it consistently hurts to arch then it absolutely reasonable to avoid it for a bit and to train a new pattern. But I would do this regardless of the hinge.
Relevance to all movements
I think we can say this about almost ever movement pattern. Its difficult to describe something as inherently faulty (knee valgus, pelvic drop, spinal flexion, butt wink). All of these things happen. There might be times when a different strategy is better for performance and there might be times when a different strategy is better to decrease pain. But they all aren’t inherently faulty.