In redesigning my sewing space I read a book about designing a quilt studio and it stressed the ergonomic issues faced by a quilter. I followed the directions and made a lot of changes in my set up and have virtually rid myself of the back pain. First you sit with your knees and hips at a 90 degree angle (which places your thighs horizonal to the floor). Have a friend look from the side to help you get the proper height of chair. Then check what your table height should be - you got it - your arms should be horizonal to the floor with a 90 degree angle at the elbows. Where your hands are is the height suggested for your table. I found that my table was about 1 1/2 inches too high and if I raised my chair then my legs were out of alignment, so I ended up building a small platform that raises my chair and foot pad (and has a raised edge so I don't roll off!). I wasn't a believer before, but have had no significant pain since doing this. It was a fair amount of work to get it set up, but now I can quilt as long as family and commitments allow!