From Medical News Today, Don't Sit Up Straight, It's Bad For Your Back.
It seems that sitting up straight, something many of us are taught from a very early age, is not good for your back, say researchers from Scotland and Canada. They found that sitting up straight strains your back unnecessarily. Ideally, you should lean slightly back, at an angle of about 135 degrees, they say.
The researchers, at Woodend Hospital, Aberdeen, Scotland, used a novel form of MRI (magnetic resonance imaging) on 22 healthy volunteers to identify which positions are best, and which are worst, for our backs. The Positional MRI Machine allows the patient to move around during the examination.
The volunteers were asked to sit in three different positions:
1. Slouching. The person hunches forward, with feet touching the floor.
2. Upright, at 90 degrees, with feet touching the floor.
3. Relaxed, reclined backwards at 135 degrees, with feet touching the floor.
Measurements of spinal angles, spinal disk height, and movements were taken. When undue strain is placed on a disk, it moves - often out of place. The researchers found that the upright position, at 90 degrees, caused disks to move the most, while the relaxed position (135 degrees) caused disks to move the least. In other words, the upright position is the worst for the back, while the relaxed position is the best.
Study leader, Dr. Waseem Bashir, University of Alberta Hospital, Canada, said "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."