I'd concur with that. Personal annecdotal evidence from working at a job that have bendy chairs often leaves me with a crick in my neck. If you sit like the f

I'd concur with that. Personal annecdotal evidence from working at a job that have bendy chairs often leaves me with a crick in my neck. If you sit like the far right picture you're going to get a forward leaning neck in any case. Further point: do these people have bad backs because they don't do any abdominal work? I've done pilates for a year and that seems to have helped a fair bit - better inner muscles and hence better posture.