Your mother probably told you, as her mother told her: sit up straight. Whether at table, in class or at work we have always been told that sitting stiff-backed and upright is good for our bones, our posture, our digestion, our alertness and our general air of looking as if we are plugged into the world.
Now research suggests that we would be far better off slouching and slumping. Today’s advice is to let go and recline. Using a new form of magnetic resonance imaging (MRI), a team of radiologists have found that sitting up straight puts unneccesary strain on the spine and could cause chronic back pain because of trapped nerves or slipped discs.
The ideal angle for office workers who sit for long periods is about 135 degrees. It might make working at a computer impractical but it will put less pressure on the spine than a hunched or upright position, the researchers say.
The study at Woodend Hospital in Aberdeen involved 22 healthy volunteers who had no history of back pain or surgery. They adjusted their posture while being scanned by a movable MRI machine, assuming three sitting positions: a slouch, with the body hunched forward over a desk or video game console; an upright 90-degree sitting position; and a relaxed position where the patient reclined at 135 degrees but kept their feet on the floor.
By measuring the spinal angles and the arrangement and height of spinal discs and movement across the positions, the radiologists found that the relaxed posture best preserved the spine’s natural shape.
Waseem Amir Bashir, from Edinburgh, lead author of the study, said: “When pressure is put on the spine it becomes squashed and misaligned. 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.
“Sitting in a sound anatomic position is essential, since the strain put on the spine and its associated muscles and ligaments over time can lead to pain, deformity and chronic illness.” Dr Bashir, who now works at the University of Alberta Hospital in Canada, presented the research yesterday at the annual meeting of the Radiological Society of North America (RSNA) in Chicago.
The study was the first of its kind because MRI scan- ning has previously required patients to lie flat.
Back pain is the cause of one in six days off work and about 80 per cent of Britons are expected to suffer from it at some point. Office workers and school children may stave off future back problems by correcting their sitting posture and finding a chair that allows them to recline, Dr Bashir said.
He added: “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, The best position for our backs is arguably lying down, but this is hardly practical.”
However, Gordon Waddell, an orthopaedic surgeon at the Glasgow Nuffield Hospital, said that the link between biomechanics as shown in MRI scans and preventing back pain was still very theoretical.
It was “human nature” to develop back pain, he said. “Like a headache or a cold, it seems we all get back pain and most of the evidence suggests that sitting position does not make a difference.”
— Non-specific back pain accounts for about 5 million lost working days per year, one in six of the reported total, costing the economy at least £5.7 billion
— In 2004-05, 452,000 people reported suffering back pain caused by, or made worse by, work
— About a sixth of the total were new cases
— Back-pain sufferers took an average of 19 days off per person last year and 11 per cent of the 2.8 million claimants of incapacity benefit said they had a musculoskeletal disorder
— 40 per cent of adults have suffered from back pain lasting for more than a day in the previous 12 months Source: Health and Safety Executive, ONS