The idea of I/O Brush is to let the kids build their own ink. They can take any colors, textures, and movements they want to experiment with from their own environment and paint with their personal and unique ink.
I have found it helpful to do the stretching exercises my physical therapist recommends. Do some core strengthening exercises, such as the ones highlighted at The Mayo Clinic. By keeping your core strong, your back won't put itself in a position to cause that sciatica pain you are having.