Nov. 29, 2006 -- Lean back before reading this; your back may thank you.

A new study suggests that sitting upright for hours at a time -- for example, when working at a computer -- may lead to chronic back pain. Instead, the best position for your back is somewhat reclined, sitting at a 135-degree angle rather than the 90-degree angle most office chairs are designed for.

"A 135-degree body-thigh sitting posture was demonstrated to be the best biomechanical sitting position, as opposed to a 90-degree posture, which most people consider normal," says researcher Waseem Amir Bashir, MBChB, clinical fellow in the department of radiology and diagnostic imaging at the University of Alberta Hospital, Canada, in a news release. "Sitting in a sound anatomic position is essential, since the strain put on the spine and its associated ligaments over time can lead to pain, deformity and chronic illness."

Bashir presented the results of the study this week at the annual meeting of the Radiological Society of North America in Chicago.