This work is intended to explore the bio-mechanical factors that may determine spinal pathology that leads to backache (Low Back Pain. LBP) and serious spinal pathology.  Once identified, corrective measures can be developed.  It is hoped that it will provide a resource for chair designers so that misconceived  views can be avoided.

  • The scientific evidence identified adverse effects which occur with conventional prolonged mid-upright sitting.→
  • To avoid all the adverse effects of conventional prolonged upright sitting. the necessity  was found that included a reclined mode →
  •  For a reclined office work-chair to be practical a number of requirements are essential.   These have been covered in the The 2 TILT CONCEPT
  • A 2T prototype was tested for practicality in the Cambridge University MfI department.
  • 2T is now designated 3M (tri-modal) since the health benefits of th unstable transitional mode were recognised.
  •  A   Sit/Stand facility can be incorporated to become a 4M version workstation.    ☛OFFICE WORK-STATIONS→
  • Although originally considered outlandish in 1998, recently design is at last  moving in this direction.  The FUTURE is GOING THE 2T (4M) WAY→

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Requirements for optimising the bio-mechanics of prolonged sittingScreen Shot 2018-07-08 at 19.38.22

Partial remediations.

Partial solutionsSystems in use at present,    See ☛ REMEDIATION

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→

Screen Shot 2013-09-29 at 14.29.22Other, commonly used partial solutions include ☛ Pelvic support→,

 ☛forward tilted seat→, & Ischial off-load →

& ☛Sit/Stand→.

2T direction

The big story here, however, is that it was found that a reclined mode is the only position that avoids all the adverse effects of prolonged upright sitting.    For a reclined office work-chair to be practical a number of requirements are essential.  These have
2T concept→

Combining these requirements can be difficult to achieve but is possible in a Screen Shot 2018-07-08 at 19.44.36suitably supported reclined mode at 40-45° which conforms to spinal morphology (configuration). This alone is impractical as a work position unless a number of secondary requirements are incorporated to make this simple concept suitable and practical for a work chair.

  1. A  reclined mode which has a correctly supported, supine, stable position  for prolonged work    ☛2T reclined mode→
  2. An upright mode required for certain jobs.    ☛2T Upright mode→
  3. An unstable intermediate mode to enable a quick, easy transition between the 2T modes.    ☛2T transition mode→     With the recognition that the transition movement has physiological advantages, this has been upgraded to a ‘mode’.   dynamic seating→



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‘Sitting disease’

Compared to people who sit the least, those who spend most time in a chair have a 112 % higher risk of developing diabetes, a 147% higher risk of suffering “cardiovascular events” such as strokes and a 49%t increased risk of death from any cause.  (   Alarming but not entirely an effect of the bio-mechanics and not examined here.  However some posts are relevant.


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