Anyone who thinks that it is useful to smash a flower syrene: NO. It’s not, you are hurting her.

The bushes need to be cut. and Re-Zat. Correctly remove old, weak, sick shoots, form a crown. It is best to do this either before the start of the juice movement, or after the flowering. Certainly not during the flowering. You can cut blossoms, but not necessarily.
The cutting is done either with a sharp cutter / socket cutter, or with a sharp knife. The cut should be clean and careful - so the tree is minimally injured and the likelihood of carrying a virus or fungus is less. Large cuts are treated with garden wax, small ones will stretch and so on.

Breaking flowering branches is very harmful.