HOW DOES SITTING AFFECT YOUR BACK?
Sitting is something that we do every day, either as part of our job, commuting or after a long day of work when relaxing on the sofa. The way we sit can affect our spinal health.
Let’s first take a look at the science behind sitting and then discuss how to do it properly. Nachemson and Elfstrom (1970) studied what happens to the intervertebral discs (IVDs) during different seating positions. The pressure that occurs within your IVDs when you sit (measured between the 3rd and 4th lumbar vertebrae) is at its least when the spine and hips are at 100 and 110 degrees. Sitting with your hips at 80 or 90 degrees results in IVD pressure increasing upwards of nearly 200%. This diagram demonstrates IVD pressure when sitting in various positions according to the study done by Nachemson and Elfstrom.
Another study by Andersson et al (1974) found similar findings when they assessed how the spine is affected when sitting in a chair, at a desk, in a wheelchair and in a car. They also concluded that the highest level of pressure occurred in the flexed or forward sitting posture with the hips at 80 degrees and the lowest when the hips are at 100 degrees.
Take home message
Your seated posture matters. Optimise it with the appropriate angle such as a 10-15 degree recline, sit back in the chair and use a good lumbar support, and of course stand up regularly and get moving as often as possible!