A group of scientists from Scotland and Canada -- conducting research at Woodend Hospital in Aberdeen, Scotland -- have recently found that, for spinal care, sitting straight upright at 90-degrees is actually NOT the ideal position for healthy backs.
Using a form of magnetic resonance imaging (MRI), the team of researchers studied how sitting positions can strain one's back. Twenty-two volunteers, all with healthy backs, participated in the study, wherein their backs were scanned by a positional MRI machine. Participants assumed three positions to test the strain each had on the body: these positions included a slouching position (body hunched forward to simulate leaning over a desk or video game), a 90-degree (straight back) position, and a "relaxed" position where the participant leaned back at 135-degrees with feet flat on the floor.
Measurements were then taken of the spinal angles, spinal disk height, and spinal disk movement (disk moving out of place due to weight-bearing strain) for each of the three positions.
Interestingly, disk movement was most pronounced with the 90-degree upright position!
However, the slouching position was associated with reduction in spinal disk height, which meant a high rate of wear-and-tear on the lowest two lumbar vertebral regions of the spine.
The team went on to report to the Radiological Society of North America that leaning back to about 135 degrees is in fact the better seated position to minimize lower back pain -- because there was less disk movement in this "relaxed" posture, thus suggesting less strain on the spinal disks, back muscles, and tendons.
Essentially, the researchers state their study definitively reveals that the 135-degree "relaxed" position is the ideal way folks should sit, since it is the best posture for backs.
This finding is significant, given that the British Chiropractic Association has data indicating that approximately a third of the population spend more than 10 hours a day in sedentary positions -- and half of them do not even leave their desks, not even during their lunch break.
Meanwhile, two-thirds of the population likewise stays seated when at home after work.
The high percentage of time we spend sitting has led to the alarming statistic of "One in three people suffer[ing] from lower back pain [because] to sit for long periods of time certainly contributes to this, as our bodies are not designed to be so sedentary," according to the British Chiropractic Association's Rishi Loatey.
Dr. Waseem Bashir, from the Radiology and Diagnostic Imaging department of Canada's University of Alberta Hospital, led the team of researchers, and he intoned: "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."
With the scientific team recommending the "relaxed" position, Levent Caglar of the charity BackCare explains the wisdom of the finding: "In general, opening up the angle between the trunk and the thighs in a seated posture is a good idea, and it will improve the shape of the spine, making it more like the natural S-shape in a standing posture."