Exercise ball tips
If you want to replace your desk chair with an exercise ball, make sure the ball, when inflated, allows you to sit at your desk with your feet planted on the floor, advises physician assistant Cora Bilger.
The website ehow.com offers this tip: "Fix your office chair seat so you are sitting correctly and comfortably at the desk. Measure your office chair from the floor to the seat. Take that number and add 4 inches to determine the appropriate exercise ball for a seat at your desk."
A balance ball chair, which consists of an inflated ball on a molded plastic frame, is sold online, and starts at about $80. Exercise balls, also known as stability balls, yoga balls or balance balls, start at about $20.n