I believe the difference between a standing desk and an exercise ball are very different. The ball still positions you in a sitting upright position. The idea of a standing desk is to get in a completely different position and not have the weight resting on your lower back. I have long wanted a standing / adjustable desk, so that I have the option to stand for part of the day. It is not possible in my current work place so I have settled for a kneeling chair. I generally use it in the mornings and switch to a normal chair in the afternoons. It just adds an extra bit of variety in my working day. I have found that the variety has helped ease some back muscle woes.