The first way yoga helps you protect your spine, is by strenghtening your back muscles. Backbends but also poses like bridge and wheel train your back muscles while also lenghtening them.
In the spine we have several spinal discs that alow a wide range of movement of the lower back and the nexk. It's when these discs loose their strength, that we feel back pain. Our spinal discs, also dry out naturally when we age and they need movement in order to get their nutrients.
Another common problem, is when the space between two spinal discs is too narrow. In this case, a nerve in your spine may be compressed, causing severe backpain that radiates through other parts of your body.
Forward bends can prevent and heal this by creating space between the spinal discs, thus relieving the pain.
If you are amongst the great number of people that suffer from chronical backpain, I suggest you start exercising and doing yoga as soon as possible.
You can find lots of video's on Youtube with exercices specifically for lower back pain.
I hope you learned something new from this article and I wish you a fantastic and healthy New Year!