Most of us remember hearing (or have told our own children) to sit up straight. But researchers from Scotland and Canada now say that sitting up straight is one of the worst things you can do for your back.

Using magnetic resonance imaging, the researchers found that sitting up straight places strain on spinal disks, often forcing them out of place. Sitting in a relaxed position, which is described as sitting at a 135-degree angle with your feet touching the floor, places the least amount of stress on spinal disks.

 “Sitting in a sound anatomical position is essential, since the strain put on the spine and its associated ligaments over time can lead to pain, deformity and chronic illness,” said study leader Waseem Bashir, from the University of Alberta Hospital in Canada.