Health: The Best Sitting Position for Minimizing Back Stress

Dick Moss, Editor, Physical Education Update.com

Whether in school or at the office, chairs are designed to keep people sitting upright, at roughly a 90-degree angle between the thighs and the torso.

In fact, it's common for teachers to correct students who slouch in their seats by telling them to sit upright.

However, new research has shown that an upright sitting position isn't good for your back. In fact, a slight backward lean is better for you.

The Study
Researchers at the University of Alberta Hospital in Edmonton used a magnetic resonance imaging scanner to observe the spinal discs of 22 healthy subjects through several sitting angles. This new technology allows patients to move while being scanned, something that hasn't been possible in the past. It provided a more realistic view of the position of the spinal discs in response to various postures.

Results
It was found that traditional sitting position - feet flat on the floor, thighs parallel to the ground and the torso at a 90 degree angle to the floor - allows gravity to put significant stress on the back muscles and spinal discs.

Left: Traditional 90-Degree Sitting Position
Right: 135-Degree Sitting Position

Leaning forward is even worse because it causes the discs to push backward and compresses the spinal cord.

The best posture is leaning backward at a 135 degree angle. This takes almost all the pressure off the lower spinal discs, minimizing the effects of gravity. At this angle, the discs aligned perfectly, almost as if the subjects were lying on their back which is the best position for preventing back pain.

Implications
How does this information relate to you? After all, physical educators spend much of their time in the gym, and you can't change the seat angles of classroom desks anyway.

However, PE teachers can take a preventative role in the future health of your ?students. After all, it's estimated that 70-85% of North Americans will suffer from back pain at some point in their lives.

Here's what you can do:

When travelling by coach, get your athletes to recline their seatbacks (if you have read my last blog, however, you'll know not to do it in front of me) and to periodically get up and move around.
In a classroom, don't get too upset with students who appear to be slouching in their seats. They may actually be relieving the stress in their lower back.
Advise your students, when studying or working in an office environment, (which is where many of them will eventually end up), to keep their seats upright while typing or writing, but to recline periodically, for example when answering the telephone.
Ultimately, a good policy for anyone, whether sitting at a desk or driving in a vehicle, is to take occasional breaks in which you get up, move around and change the angle of your back.

Reference: Unnati Gandhi, "Was Mom wrong? Study says you shouldn't sit up straight." Globe and Mail.com, 11/08/2006. http://www.globeandmail.com

To download the pdf version of this
article, click here: Download Now