I have had a number of problems with my back since hurting it during a lift about 12 years ago - which have mostly gone away, at this point, through exercise, ergonomics, and posture control. I have to say, though, I have felt no back or neck pain using a messenger bag at all as opposed to a backpack. In fact, I wasn't even using a proper messenger bag previously, but a clunky Apple laptop bag from a software developers convention (that I did not attend). The Soma Folson bag I've just picked up is quite a bit more comfy than that Apple bag was... and hopefully more sturdy and waterproof as well. Certainly doesn't hurt my back.