that looks like an injury waiting to happen...I think all stability shit like this are just bs that the trainers come up with to be different
I had a buddy that was big into stupid exercise like this, so I told him to get a tight rope put it 2 inches off the ground and deadlift 500lbs...he said that was a stupid idea-at what point is it productive or stupid?
I told him dumbbell presses on a Swiss Ball were stupid, when are you going to lose your balance and have 100lbs of steel smash in your face???