Advice to 'sit up straight' to blame for aching backs

Researchers show Mom's advice to 'sit up straight' to blame for aching backs

at 11:48 on November 28, 2006, EST.
HELEN BRANSWELL

TORONTO (CP) - If you have a problem with lower back pain, you might want to blame it on your mother.

Mom's repeated exhortation to "sit up straight" was actually bad advice, a team of Scottish radiologists showed Monday in research presented at the annual meeting of the Radiological Society of North America in Chicago.

They used a special MRI or magnetic resonance imaging scanner to look at the pressure placed on the spine by various seating positions - a forward slouch, a 90-degree angle and a relaxed position where the knees weren't at a right angle to the floor and the back was reclined slightly.

The scans showed that sitting at a 90-degree angle puts unnecessary pressure on the disks of the lower back, which can lead to back pain, disk degeneration and sciatica.

One of the authors, Dr. Waseen Bashir of the University of Alberta Hospital, said that's because the body is actually working against gravity in that position.

"The curvature at the bottom of your back is not normal," he said in an interview from Chicago.

Bashir, who did the work while at University Hospital in Aberdeen, Scotland, said he and his colleagues found the most natural or neutral position was actually one in which the body was at a 135-degree angle - a posture that most closely approximated lying down.

That's because the psoas muscles of the back - the large muscles that run from the mid-back to the top of the leg - relax in that position, Bashir said. In the 90-degree position, those muscles are always tense.

"Once you've strained the psoas muscles as well as the back muscles and the spine you're basically going against gravity and it's not natural. That's what's causing back pain. That's what's causing the stress."

This theory has been around for awhile. In fact, Bashir's presentation featured diagrams from a 1953 scientific paper that hypothesized that this angled posture was more suited for sitting.

But no one has been able to test out the theory until now. Traditional MRIs can only scan subjects who are lying down. The Aberdeen group used a special positional MRI that allowed them to scan 22 subjects in the three upright positions, looking at what each posture did to the muscles, nerves and disks in their backs.

Pat McKee, a professor of occupational therapy at the University of Toronto, was delighted to hear about the study, saying she hopes it can help rid the world of the notion that sitting with knees, back and elbows locked at 90 degrees is a good idea.

"The idea of sitting ramrod straight is really not good for the body," said McKee, who was not involved in the research.

"It means that your muscles, your trunk muscles, have to work more."

McKee said most modern office chairs can be adapted to this more relaxed posture - but few people know how to position their workstations properly.

"Everything needs to fit together. The relative height of the seat, the keyboard, the height of the monitor, the angle of the back of the chair, the angle of even your seat pan - it's a jigsaw puzzle that in ideal situations has got the adaptability to allow you to individualize it for the person," she said.

"Unfortunately it's like running a VCR - very few people have stopped to read the manual."