Source: Beginner's Guide: How to Sit on a Stability Ball
You may think it's all fun and games sitting on a stability ball while you work, but you should implement these important guidelines to help protect yourself from accidental injury. While the stability ball has its advantages, you should avoid using one if you have an acute back injury, especially if your quadratus lumborum, the major back muscle that runs from your 12th rib to the top of your pelvis, is compromised. The ball offers no back support, forcing you to heavily depend on the QL for support. If you notice any sharp or discomforting pain, forgo the ball for an ergonomic chair. Five Rules For Proper Stability Ball Usage:
- Right size: Buy a ball that is intended for your height. Inflate the ball enough so that when you sit down, your legs create a 90 degree angle, at both the hip and knee, and your entire forearm can rest easily on your desk when typing.
- Wide stance: Place your feet flat on the floor about