Back pain is not limited to those whose work consists of heavy lifting. People who work on a computer and are seated for most of the day are just as likely to have back problems. A person sitting in a chair places more pressure on their back then if they are standing. At the same time, the weight of the upper body is placed solely on the lower back. Combined with the fact that the body is static then will cause back problems.
Movement is important to the maintainance of a healthy back.
When we move it encourages more muscles to share the load. It also means that blood is circulating to bring energy to the muscles and clear away waste products, which would otherwise leave muscles tired and sore. Have chairs that are appropriately adjusted to the person's requirements. Work activities may be varied to allow this. Stretch the muscles with proper exercises.