Backache? It does not matter how you sit or on what you sit. What does matter to your spine is how long you sit.
Potential breakdown of spinal components start after 6 hours unless your chair is bio-mechanically friendly to them. This work is intended to explore the bio-mechanical (ergonomic) factors that may determine spinal pathology and lead to backache (Low Back Pain. LBP). And derive some answers.
Sitting on a a log, a tree stump, an old dining room chair or a conventional office chair does not have a great effect on your back. It is on prolonged sitting that the bio-mechanics (ergonomics) affect spinal components. How long? Research suggests six hours or more which is common in the present work environment.
NAVIGATION through the website
For some readers this study was too large and diffuse. It is now divided into subdivisions. NAVIGATION. To use this work → Or see the top menu↑
Specialists will prefer to jump directly to their page of interest using the Right menu→.
The effects of sitting
The evidence identifies the adverse factors which occur with conventional prolonged mid-upright sitting. Described under ☛ Biomechanics→. A brief overview is shown here→
Upright sitting resulting in flexion of the lower lumbar joints, results in spinal pathology. These include permanent stretching of the posterior spinal elements and a shift backwards of the IV disc contents towards pain sensitive structures that can account
for common mechanical backache (LBP) and can also lead to serious spinal pathology. The latter has been confirmed by pMRI scans (Smith F, 2007→).
The obvious, and perhaps only, solution was for prolonged work to be performed in a chair that has a stable, correctly supported, supine reclined mode. Shown here is the Okamura ‘Atlas’ chair. ☛ Atlas→
Other, commonly used partial solutions include ☛ Pelvic support→,
The only full solution is :-
This is the big story derived from examining the bio-mechanical evidence, identifying the factors which can result in spinal breakdown on upright sitting and finally devising a concept for office work-chair design that avoids these adverse factors. The conclusion was theoretical but was later validated and confirmed by a new technology ‘positional MRI’ (pMRI). A fully compliant 2T chair is ergonomically optimised (and optimally comfortable). Anything less should be unacceptable for prolonged use.
The 2T concept addresses all the ergonomic factors that ensure a sitting position that is the least likely to perpetuate, or result in, backache and other spinal conditions. It also includes the necessary requirements to make this a user-friendly practical work-chair. Comfort is also thereby maximised. ☛A Full solution→
- A Reclined mode is the best for prolonged work. ☛The 2T reclined mode→
- A full body support that is configured to the correct spinal shape.
- Reclined mode requires head support that allows for a forward vision field.
- Variability at head and feet only. Avoided elsewhere. Adjustments→.
- Leg/foot support, which can be provided by the floor if the knees can remain extended.
- A 2Tilt Upright Mode (eg. forward tilted seat,) is subsidiary but required for certain short activities and quitting the chair and is the default mode when the chair is unoccupied. ☛2T Upright modes→
The mid ranges should be unstable and easily negotiated ☛Unstable intermediate mode →. This is to avoid the conventional adverse mid-upright sitting posture. It can be used for short periods as a form of exercise ( ☛ dynamic seating→), particularly for rehabilitation following an acute attack of Backache.
This leads on to the 4Modal, 4M work-station.
- Reduced office footprint.
- 2T requirements easier to achieve.
- Easy to move about & around.
- Allows short periods of sleep ( ☛MetroNaps→) 2T in the office and ☛4M work-station→
Perception & Reality. Familiarity bias
Western people have sat in an upright chair since childhood resulting in Familiarity bias. They have been indoctrinated that mid upright sitting is ergonomically ‘correct’. Chair designers have ensured comfort. Therefore it is not surprising that most people perceive this as correct and desirable. It will take time to change this misconceived perception. First chairs designed on bio-mechanically correct lines must be manufactured. Their advantages need to be explained. I have noticed that people who are liable to backache immediately recognise the advantages and are likely to be the first to create a demand. The newer generation is already more open to fresh ideas and also take quickly to a 2T design.. Insurance is already begining to take an interest (personal communication). HAS