I read twice and now I'm still asking myself if I maybe didn't understand you right
You KNEEL on a swiss ball, and, if that wasn't enough, you then raise your arms and bend over holding a broomstick in your hands?!
I wish I could balance sitting/lying on a swiss ball for some seconds without doing anything... (I could picture myself doing the above, but the broomstick would need to be a Nimbus 2000...)