If you don’t have back pain, it’s a good idea to stay active and maintain a strong back and, equally important, strong abdominal muscles. Researchers aren’t sold on the benefits of any particular ergonomic chair for preventing back injuries or back pain. For that reason, even if you did get an ergonomic chair, there’s no guarantee that it would be helpful to you.
If you do end up with a sore back, it may be due to other issues, not related to work, such as the way you lifted something at home, an traffic accident or sudden stop in the subway, things like that.