This go-to mobility exercise for the lower (Lumbar) spine area is well known for a reason. It helps balance out that loss of the natural lumbar curve that commonly occurs when sitting - which happens a lot in our modern day lifestyles. If possible spend 5 minutes with a heat pack / warm water bottle on the lower back before starting the exercise. Remember, don't force it, just encourage the movement.
*If your back pain could be disc related rather than muscular, then best to check with a physiotherapist first.
Hope this is useful & visit Book Sports Massage Hull for more help.