Sit Back, It's Better for Your Back
Long Hours Sitting Up Straight May Cause Back Pain, Study Shows
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
Bashir presented the results of the study this week at the annual meeting of
the Radiological Society of North America in Chicago.
Comparing Sitting Positions
Back pain is one of the most common causes of work-related disability in the
U.S. and helping to identify bad seating postures may help protect the spine
and prevent injury.
Using "positional" magnetic resonance imaging (MRI) researchers
studied the sitting positions of 22 healthy volunteers with no history of back
pain. The MRI machine allowed freedom of motion, such as sitting or standing,
during imaging. Conventional MRI machines require the patient to lie flat and
may mask some causes of back pain.
Researchers used the MRI to examine spinal positioning while the
participants assumed three different sitting positions: slouching forward (such
as hunched over a desk or video game console), an upright 90-degree sitting
position, and a relaxed position with the back reclined backward about 135
degrees while the feet were still on the floor.
Overall, researchers concluded that the 135-degree reclining position put
the least stress on the spine and may reduce the risk of back pain. They
recommend that people who sit for long periods of time correct their sitting
posture and find a chair that allows them to recline.
"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," says Bashir. "Employers could also reduce problems by
providing their staff with more appropriate seating, thereby saving on the cost
of lost work hours."