MRIs set researchers not-so-straight about posture

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What is typically considered good posture might not be so good after all. Research unveiled today at the annual meeting of the Radiological Society of North America (RSNA) in Chicago shows that sitting in an upright position places considerable strain on your back. The researchers from Woodend Hospital in Aberdeen, Scotland, used MRI scans to lead them to the conclusion that such back position could lead to chronic pain if you sit in such positions for long hours each day.

"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," said Waseem Amir Bashir, MBChB, FRCR, author and clinical fellow in the Department of Radiology and Diagnostic Imaging at the University of Alberta Hospital, Canada. "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 and colleagues through their work hope to help people reduce back strain by allowing them to take preventative measures to protect their spines.

"We were not created to sit down for long hours, but somehow modern life requires the vast majority of the global population to work in a seated position," Bashir said. "This made our search for the optimal sitting position all the more important."

The researchers evaluated 22 people with no history of back pain or surgery, and acquired images using a "positional" MRI that allows patients to sit or stand during imaging. During the scans, each patient assumed three different sitting positions during which measurements were taken of spinal angles and spinal disk height and movement across the different positions.

The scan revealed that disk movement is most pronounced with a 90-degree upright sitting posture. On the other hand, it was least pronounced with the 135-degree posture, indicating that less strain is placed on the spinal disks and associated muscles and tendons in a more relaxed sitting position.

Bashir and colleagues now advise patients to sit in an optimal position of 135 degrees.

"This may be all that is necessary to prevent back pain, rather than trying to cure pain that has occurred over the long term due to bad postures," he added. "Employers could also reduce problems by providing their staff with more appropriate seating, thereby saving on the cost of lost work hours."