Balance Ball A medicine ball is also commonly used by athletes who have sustained an injury, and seek rehabilitation. They are also extensively used by secondary schools as a fitness aid, by lifting the ball, or performing different exercises with the ball incorporated to increase the strain on a particular muscle. What is A Swiss Ball? A Swiss ball is a ball constructed of elastic rubber with a diameter of around 55 to 85 cm (22 to 34 inches). It is used in physical therapy and exercise. Yoga with Balance Ball? Sit on The Ball! Sitting on a ball instead of a chair is a great way to keep your spine healthy. Try to sit on a ball for at least part of your work day, if you have a desk job. When you sit on a ball, you’re forced to sit up with good posture because you have nothing to lean back on. Also, because the ball rolls around, it keeps you on your toes and keeps your body moving, which help prevent the stiffness and back pain that you can get from being too sedentary. B...