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Backache? Sitting upright could be culprit

Nov. 27, 2006
Courtesy Radiological Society of North America 
and World Science staff

“Dignified” might not always equal healthy. Sit­ting straight up­right strains the back un­nec­es­sar­ily, caus­ing po­ten­tially chron­ic pain prob­lems over the long run, a new study has found.

The sci­en­tists pre­sented the find­ings Nov. 27 in Chi­ca­go at the an­nu­al meet­ing of the Ra­di­o­log­i­cal So­ci­e­ty of North Amer­i­ca.

Sit­ting at 135 de­grees rath­er than 90 de­grees could im­prove back health, re­search­ers say.


“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 of the Uni­ver­si­ty of Al­ber­ta Hos­pi­tal in Can­a­da, one of the re­search­ers. 

“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.”

Back pain is the most com­mon cause of work-re­la­ted dis­a­bil­i­ty in the Unit­ed States, ac­cord­ing to the Na­tion­al In­sti­tute of Neu­ro­log­i­cal Dis­or­ders and Stroke. 

“We were not cre­at­ed to sit down for long hours, but some­how mod­ern life re­quires the vast ma­jor­i­ty of the glob­al pop­u­la­tion” to work sit­ting, Ba­shir said. 

His team stud­ied 22 vol­un­teers with no his­to­ry of back prob­lems, us­ing a new form of an ex­ist­ing tissue-scanning tech­nol­o­gy, mag­net­ic res­o­nance im­ag­ing. The new “po­si­tional” ver­sion of the scan­ner lets pa­tients adopt dif­fer­ent po­si­tions, rath­er than hav­ing to lie flat as with the tra­di­tion­al machines. 

The vol­un­teers sat three dif­fer­ent ways: slouch­ing, or hunched for­ward; up­right, a 90-degree po­si­tion; and “re­laxed,” lean­ing back­ward 135 de­grees with feet on the floor. 

Spi­nal disks are prone to risky shifts when the spine car­ries weight, the re­search­ers said; this was most pro­nounced at 90 de­grees and least at 135. Slouch­ing re­duced spi­nal disk height, indicating wear and tear on low­er spi­nal lev­els, they added.

Across all mea­sure­ments, the re­search­ers con­clud­ed that the 135-degree po­si­tion fared the best. “This may be all that is nec­es­sary to pre­vent back pain, rath­er than try­ing to cure pain that has oc­curred,” Ba­shir said. “Em­ploy­ers could al­so re­duce prob­lems by pro­vid­ing their staff with more ap­pro­pri­ate seat­ing, there­by sav­ing on the cost of lost work hours.”


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Sitting straight upright strains the back unnecessarily, causing potentially chronic pain problems over the long run, a new study has found. The scientists presented the study today in Chicago at the annual meeting of the Radiological Society of North America. “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 of the University of Alberta Hospital, Canada, one of the researchers. “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.” Back pain is the most common cause of work-related disability in the United States, according to the National Institute of Neurological Disorders and Stroke. “We were not created to sit down for long hours, but somehow modern life requires the vast majority of the global population” to work sitting, Bashir said. His team studied 22 volunteers with no history of back problems, using a using a new form of an existing tissue-scanning technology, magnetic resonance imaging. The new “positional” version of the scanner lets patients adopt different positions, rather than having to lie flat as with the traditional machines. The volunteers sat three different ways: slouching, or hunched forward; upright, a 90-degree position; and “relaxed,” leaning backward 135 degrees with feet on the floor. Spinal disks tend to move when the spine carries weight, the researchers said; this was most pronounced at 90 degrees and least at 135. Slouching reduced spinal disk height, signifying wear and tear on lower spinal levels, they added. Across all measurements, the researchers concluded that the 135-degree position fared the best. “This may be all that is necessary to prevent back pain, rather than trying to cure pain that has occurred,” he added. “Employers could also reduce problems by providing their staff with more appropriate seating, thereby saving on the cost of lost work hours.”