Office workers have long been told to sit up straight at their office desks to try to avoid getting a bad back.
But now, after scientists have found that sitting bolt upright may actually make back problems worse, that advice may have to be ignored.
Research has found that an erect posture puts too much strain on the spine and can trigger chronic pain.
Instead of sitting with your back upright, you should instead lean backwards until you reach an angle of 135 degrees.
Experts are therefore advising people who spend long hours at their desks to alter their office chairs to a more relaxed position.
They believe this may be the best way to prevent back pain, which is thought to be affecting a third of Britons at any one time.