I have recently been experiencing lower back pain from sitting improperly. So i came across this 2006 study that suggests 135 degree is the best: http://news.bbc.co.uk/2/hi/6187080.stm This was very surprising to me, since all my life i have been told by well-intention ed people to "sit straight". I hear it all the time on the media as well (from things like movies, not documentaries) what do you think? From personal experience, observations, and other scientific research, do you think 90 degree angle or greater than 90 degrees is better, ergonomically speaking? I know from personal experience that < 90 is bad for the back.