It is necessary to do this movement after warming up the spine otherwise it will hurt your bone.

This is the bridge with elevated heel, it is to make the waist at the higher position to have a bigger arch.

This is Mini-kana Sensei who has great ability of lean back however don't imitate it if you don't reach this level as it requies a lot of training to have flexible body. If you a beginner it is too dangerous to do it.

Developping more stomatch muscle and stretching ability it will be easier.