I have a history of back and other joint pain. So after I retired and considered the possibility of playing the guitar again, I tried various types of chairs. Some chairs caused discomfort immediately. Others produced the discomfort after a month or so. But I found one chair which I comfortably practice on daily for 6 months. This chair is a weight bench.
I would understand if the reader questions the reason for using or considering a weight bench. I probably would have never considered it but, as I work out 6-7 days a week at a gym, I came to appreciate that these benches were actually very comfortable (at least, for me). So when thinking about the underlying mechanics, I realized that a weight bench is a platform designed to support one portion of the body as the muscles of another part are exercised with weights. In my application, I want to play the guitar while supporting the weight of my upper torso, arms and head and reduce the force their weight would have on the lumbar region of my spine and my tail bone. I know this sounds more like wishful than human engineering. And I don’t know how better to explain or describe my use of a weight bench. I wanted to provide a photo of me sitting with the guitar but I was unable to find someone to help photograph. I did photograph the weight bench by itself and perhaps my description below will suffice.
As shown in the photo below, I set up the weight bench with the backrest and seat reclined. As the seat is narrow, my legs straddle the seat (just as if I were riding a bicycle). So my thighs are actually tilted slightly below – not above --- the horizontal. Only the lumbar region of my spine is supported against the backrest. My upper back and head do not make contact with the backrest but rather maintain a perpendicular posture. (For those mechanically inclined: The weight of my upper body is partially supported by the floor through the legs of the weight bench).
While the angle of the backrest and seat are adjustable on my weight bench, the adjustments are too coarse. So to fine tune the location of the support on my back, I use a cushion which I can slide up or down along the backrest.
Hope this might help those with back problems or at least inspire them to explore other possibilities.