The ideal sitting posture for computer uses must address two adverse factors:

1. Static Compression of the Spinal Base
2. Sustained Postural Strain of the Neck

Optimal spinal alignment of a gentle S-bend (viewed  from the side) helps defray compression, particularly during prolonged sitting.

The Ideal Sitting Posture for Computer Users Must Minimise Compression

Compression of the spinal base is straightforward. The bricks at the bottom of the stack take more weight and the spine settles down on itself, like a concertina squashing down at one end. Each day, lumbar discs lose 20% of this discal fluid, which they mostly get back at night during sleep. However, lumbar discs lose about 10% – half their daily quota of fluid – in the first two hours of sitting. Unfortunately, a C-bend spinal alignment, typical of the fixed and crumpled nature of computer postures, drives even more fluid out of the lumber discs. 

Compression on the spinal base is greater when C-bend sitting with the upper body in front of the line of gravity.

With hours of computer sitting your lower discs gradually lose the ability to rehydrate with fluid overnight so they become progressively drier and flatter. They cannot pull apart again to imbibe fluid, even when you're not sitting on them. As  the spine becomes more brittle it cannot roll with the punches – the incidental jolts of every day life – and is easily injured. 

All lumbar intervertebral discs lose 20% of discal fluid through the course of each day, but they lose half that within the first two hours of sitting.

Here's How Computer Users Must Deal with Basal Compression

Proper Lumbar Support

Stopping the spine slumping into a C-bend goes a long way towards reducing the harmful effects of sitting. An ergonomic chair with a prominent lumbar support (most aren't prominent enough) helps prop up the spine from below, helping to defray lumbar compression. If you don't want to run to that expense (all ergonomic chairs are expensive) a firm pillow is just as good. But it must be positioned right in the small of the back – not too high obstructing the shoulder blades and not too low either. 

Squatting
 
Just a moment or two of dropping down into a squat when you get up from your chair makes all the difference. Squatting is Nature's way of decompressing-on-the-run, although the forces of distraction are greater with holding on as you see here. Always try to get up an squat at your desk within two hours as this pulls fluid back into the discs. 

Daily Lumbar Decompression

A simple BackBlock regime at the end of every day is the most proactive, effective and inexpensive way to undo the adverse effects of the sitting posture of computer users. The passive hyper-extension in the supine position, with the block under the sacrum, pulls the spinal segments apart and keeps the lower back more compliant. You can read here How To Use The BackBlock  and Why The BackBlock Works. 

See here to purchase a Sarah Key BackBlock from Amazon

The Ideal Sitting Posture for Computer Users Must Minimise Neck Strain

The human head is very heavy - approximately 5 kg - and even heavier when stuck forward, in front of the line of gravity.  Trapezius, the muscle at the back of the neck and cross-bar of the shoulders, controls forward angulation of the neck. With a prolonged C-bend postures  it works overtime, like horse's reins, trying to hold the head up and this is a great strain. Muscle fatigue creates waste products that stimulate nerve endings, causing the typical twinges and achey-tired muscles at the base of the neck.

Trapezius overactivity also compresses the vertebrae of the neck and upper back, causing the beefy mass known as a dowager's hump. The compression also reduces neck mobility, while the upper body becomes more stooped. The shoulders also stiffen as the pectoral muscles across the top of the chest adaptively shorten.

Here's How Computer Users Must Deal with Neck Strain

Proper Desk-Computer Setup

Keeping a spinal S-bend while sitting also puts the head in a better position, with less muscle effort needed to balance. The only way of creating the ideal sitting posture for computer users is to raise the screen to eye-height, which stops the forward angulation of the neck.  Some laptop users invest in a seperate keyboard and then elevate the laptop on a stack of books. Correct desk/chair/keyboard height should mean that you don't have to hitch the shoulders for your hands to clear the keys. Proper desk height lets the forearms hang at an obtuse angle at the elbows.  

Daily Spinal Decompression for the Upper Back and Neck

Using the BackBlock for the upper back gives you a breath of life, making  you feel looser in your own skin. It winches your spine back and undoes the typical computer posture hunch, while at the same time it opens the shoulders and untethers the pectoral muscles. You can read here in depth about using the BackBlock as the effective Upper Back Treatment 

Some Related Pages

• How to Sit at a Computer
  
  
• Proper Sitting Posture at a Computer
  
  
• Back Pain on Sitting