Sarah Key has forwarded to me a useful information sheet on the importance of sitting well. It gives a good visual of our spine and how it can need supporting when sitting.
Sarah Key © 2006
Sitting is an essential posture in our modern way of life, even though it is quite ‘new’ in an evolutionary sense. Earlier civilizations did not sit with a hard surface rammed up under the base of their spines. Instead they squatted, which is Nature’s way of pulling the spinal segments apart longitudinally from below and naturally ‘decompressing the spine’. Being a vertical stack, the bricks at the bottom suffer greater compression from the super-incumbent weight. The water-filled fibro-elastic cushions called the intervertebral discs naturally leach fluid through the course of each day (20% thru the day) and regain it at night while we are relaxed and horizontal while asleep. Sitting squashes the discs more and we lose the IVD fluid faster (10% in first 2 hours of sitting). But – and here’s the clue- sitting slumped in a ‘C’ bend rather than maintaining your natural ‘S’ bend squashes the basal discs even more. Just as bad is sitting perched up rigid with your spinal muscles working overtime to hold you up. This causes almost screaming agony in a matter of minutes. The reasons for this are twofold: thousands of Newtons of compressive forces pinches the discs even more, plus the build-up of lactates (or waste products) in the paraspinal muscles themselves from the un-ending contraction (normally these are sluiced away in the periods of inactivity when muscle fibres are relaxed and the muscle off duty).
METHOD. You have to keep a relaxed ‘S’ bend of the spine while sitting and never hold yourself rigidly perched upright – ever! The best thing you can do while you are in recovery mode from your crisis is mould a normal bed pillow behind your low back (you can tie it around your waist if travelling far, the tie goes where your arm bends to a right angle across your back) and then move right to the back of the chair and RELAX back, your back off duty – and letting your belly go (yes, I’m giving you the license to let your belly hang out!). If you try to hold yourself up rigid when your back is bad you will make yourself steadily worse. Indeed, sitting rigid like this is one of the main ways of making a bad back worse.