I sew standing at my cutting table. I find it much more comfortable and way less shoulder and neck pain. It is so much easier to move around to the ironing board, cutting board, getting coffee, etc. than getting up and down. Sometimes I| even put the foot pedal on the table and operate it with my hand (thinking of the hand-crank machines, and how they operated them).

Nova had a program just last night about the ergonomics of standing and not sitting down in chairs. Their conclusion was never sit down except for a short period of time each time; the body is much better off when you stand and move around.

I know potters and office workers who work standing up because of back problems. I think what works for you depends on what part of the back has problems. I would suggest a rubber mat to stand on and take breaks or dance to a CD while sewing.

I too sew standing up. I didn't years ago, but after surgery left me with a spine/rib issue resulting in severe scoliosis, I lost 4 inches in height. Now, at only 5'2", I have a harder to seeing my work if I sit and sew, no to mention because I sew at a kitchen table, I have to lift my arms and this causes me additional shoulder, neck and upper-back pain, of which my surgery left me with plenty of already. By standing I have a great viewing angle, and my arms are in a downward reaching position, which causes less strain on my shoulders. I've tried using an elevating office chair, but find myself standing and sewing after ironing or such. Plus, I'm sure it burns a lot more calories to stand, much healthier than sitting for long periods.