Category Archives: Uncategorized

The FUTURE is going the 4M way

From a wierd concept in 1998 to become disruptive in 2017?

The ‘Deskless Chair’ derived from the ergonomic importance of a reclined work position, is morphing into the ‘Workstation’. This should reduce the incidence of LBP and other health issues.

In 1903 Ford’s ‘Horseless Carriage’ had morphed into the Model T, capable of 20 horsepower In 1908.  This, at least, solved the “great horse manure crisis of 1894” when it was suggested that London’s streets would be clogged in 9 feet of horse manure in 50 years. It’s descendants are, in turn, being disrupted by ‘the driverless car’.

Screen Shot 2017-05-23 at 07.28.24Disruptive technologies have to prove themselves first. They do so by working on the same infrastructure as the incumbent leaders. Cars had to run on the same streets as horses. Dial-up internet connections in the late 1990s used the copper in the phone networks.  (Dan Denning
Publisher, Southbank Investment Research ).   So, work-stations have to use existing office spaces before becoming universal.

We are seeing a number of ‘work-station’ type models which include a reclined work mode and so are superior to the present (2016) upright conventional  models.  The models shown here are a step in the right direction but are not 2T compliant and appear to ignore the science and are based on engineering.    They do not invite a great uptake, in spite of extensive PR.

the Altmark

AltmarkNow, in 2015, a chair is proposed,  that has at least an upright and reclined work position.  Did they see my web-page for the 2T concept which has been in the public domain since 1998, later upgrade to the 3M (2T = 3M) & 4M the optimised default  against which the ergonomics of any chair can be assessed?  Or did they arrive at this independently?    It was probably the latter and the chance of a simpler, more ergonomically optimised and more elegant model was missed       I have not seen this model but however deficient in biomechanics (ergonomic) optimisation, with reservations, it is  potentially the best work-chair in the market. (

For a fuller account see in → WORK-CHAIRS, a new breed with a reclined mode.


Screen Shot 2016-06-24 at 12.34.17A good idea in that it achieves the 2 modes that I have been advocating since 1998, but what a terrible design!   Electrically operated.  With all possible bells and whistles It represents an almost opposite view to the 2T principle and it’s 4M workstation derivative.   This  with an emphasis on anatomy and spinal biomechanics leads to lack of adjustments and simplicity.  Obviously a huge misplaced engineering enterprise without awareness of what was possible and desirable.  Another example of what emerges when the the optimised default solution of the 2T concept is ignored.           Price: $5995

The CHOTTOScreen Shot 2017-05-20 at 11.14.27

This highly innovative chair was introduced to me by it’s designer,Thomas Stroman, the Founder of Stroman Design.   He wrote to me “I am an architect by training, but having experienced back surgery, my focus has been on ergonomic seating design for human-computer interaction.

At first glance I might be excused for thinking that it looked as if it were self mobile with caterpillar tracks.  Perhaps an exciting concept for the future. What fun to go charging around the workspace and bumping one’s colleagues!

Screen Shot 2017-05-20 at 11.11.16The importance of a reclined work position has been recognised.  It could be modified to become virtually 2t (4M) ergonomic compliant.  A foot rest has been incorporated,



IfM 2013Now have a look at the 2013 Cambridge student project on the 2T CONCEPT.    The Cambridge trials showed the elegance, simplicity, cost effectiveness  and greatly enhanced ergonomics of th 2T concept showing a 4M version.

It excited much comment along the lines “Gee!  That’s cool.  I want it”.  The lack of ‘familiarity bias’ is typical with the millennial generation.  Go consider.

(Yes!   That’s John Gorman glowering in the background.  He was an engineering graduate and took the opportunity to visit his ‘Alma mater’).

And a sketch for a 2T model done for me by Aaron Chetwynd in about 2000, which deliberately resembles existing chairs so as to avoid familiarity bias.

For further reading, see ☛


Screen Shot 2017-05-20 at 11.14.27

This highly innovative chair was introduced to me by it’s designer,Thomas Stroman, the Founder of Stroman Design.   He wrote to me “I am an architect by training, but having experienced back surgery, my focus has been on ergonomic seating design for human-computer interaction.  Over the past three years I have designed, prototyped and patented the Chotto® ( chair + ottoman ) .  It is a uniquely human-centric and recumbent seating / task-seating / standup desk that positions the body
into close proximity to the neutral body posture that is produced in microgravity.”  “I believe  this field of study is increasingly important and needs to be pursued given the scope of benefits it can provide those who must sit by choice or physical condition. I would also like extend an open invitation to you to evaluate my prototypes if you are ever in NYC.    Regards,  “

An excellent objective and a very interesting product.  At first glance I might be excused for thinking that it looked as if it were self mobile with caterpillar tracks.  Perhaps an exciting concept for the future.    I wrote back (May 19, 2017)

Dear Tom    I have had another look at your web page​  At first sight, I admit, I thought the Chatto to be OTT.  But on second thoughts, some might find it attractive, including me, to charge around an open plan office floor in a mini-tank.  But I can see it excites ‘familiarity bias’.  I can see no reason why it cannot be modified to take advantage of the 2T ergonomic optimisation.   This would be a huge selling point.  Even the Chinese put ‘health’ as their top design requirement  Unlike our chair manufacturers who put ‘comfort’.  (See ).Screen Shot 2017-05-20 at 11.11.16
In the early model, above, I was worried about the apparent calf compression that has the potential for DVT.  “An optional footrest elevates the legs and feet while an immediately mobile, nested and freely rotating task tray provides a universal surface for eating, reading, writing, or digital interaction. This same tray can be repositioned within the optional rear support brackets for use with the pivoting display interface / standup desk ( PDI ).  The PDI is based on design research that favors a human-centered interface that literally revolves around the seated, tension-free and fully supported Screen Shot 2017-05-20 at 11.07.26user.  If paired with a laptop, the PDI can also be used as a dual-screen interface in both the seated or standing position.  With the PDI in the default standup desk position, the Chotto simultaneously accommodates both a standing and seated user – all within a small 15 s.f. footprint.”

Also the user is very happy but looks trapped.   How does she get out?   Leg support is unecessary as it is provided by the long bones of the leg but a foot rest is essential, padded support for the heels, for prolonged work but not for the upright mode.

Screen Shot 2017-05-20 at 11.08.23Dear Tom.     Looking at your diagrams, I would make the following points from the bio-medical viewpoint :-
  • You have a good reclined work position.  But the Chair /body shape interface requires  iliac support at 20 cms above the seat pan. This is important for spinal wellbeing.   (See  bottom half).
  • You have correctly spotted that good design encompasses most body shapes and sizes.  Adjustment is only needed at the extremities, neck and legs.   (See ).
  • I like the way your computer screen adjusts to whichever mode.
  • For full 2T compliance I make a point for the intermediate ranges to be unstable for additional health benefits.  Of course, this is not basic (See & ).
  • On further thought, I do not think that a lordotic concave support for the kyphotic/convex thoracic spine, as described in the 2T is strictly required.  The thoracic joints are stable being splinted by the ribs.  Only rotation movement occurs at this spinal level.
    Your configuration depends on the convex shape of the wheel circumference and this can support the fairly solid thorax, providing that it is accompanied by neck/head support in the reclined mode.  You will be glad to hear that I have tested this while having my bath.  In the UK we have prolonged baths and so can think great thoughts.  The iliac support, lower down at the lumbar-sacral junction is very important but can be effected by padding as you have suggested,

Another architects chair

Screen Shot 2017-05-20 at 13.48.22Architects have a tradition for designing good furniture. Aaron Chetwynd did this 2T sketch for me. It is deliberately ‘office chair’ looking to reduce ‘familiarity bias’.   It is not intended to be a work-station.

Screen Shot 2017-05-20 at 13.37.15

The leg/foot-rest design is important and is wrong in the Aaron view above. There is no need for a leg rest as this is effected by the strong long bones of the leg (Lower end of the femur & lower leg tib/fib).  However this brings point pressure onto the heels which I found to be painful over time and needs to be well padded.  I think your design shows this except the pressure seems to be at the ankles.  This may need further consideration. Also it needs adjustment for leg length.  Pressure on the calf muscles should be avoided as it may limit venous return and cause Deep Vein Thrombosis.
New point
Screen Shot 2017-05-22 at 17.22.25



About the Chotto:

Design details


Being the interface btween body shape and chair, it is important that the Reclined mode configuration should be correct.  If not it can engender discomfort (as can be experienced in certain dentists chairs) and more important is potentially dangerous.

  • Since these ‘shell’ components are intended to describe a seat’s supporting interface with the human body, when completed the Shell Chair forms could be employed to assist in creating an actual shell-based seat in various possible ways:
  • Shell1Shows that a slightly flexed thoracic spine + the upper lumbar joints is not adverse.
  • An office version would be narrow with a small telescopic headrest to address height variation and to reduce footprint.
  • Iliac support is included to prevent lumbar spine sagging in the relaxed mode
  • Shoulder width to allow people with broad shoulders to have full movement without laterel constraint.
  • In this assay the headrest is wide to include audio speaker components for home use.


  • Moulded alone in a thin rigid material (as with Aaro Aalto’s ply furniture or the Knoll Saarinen).  Graphene is obviously relevant.
  • Moulded to form a base shell carrying relatively thin textile/foam skin padding (Eero Saarinen Knoll and Eames Vitra collection).
  • As a final form around which a tensile mesh or textile ‘hammock’ design could be generated (Herman Miller Aeron and Knoll Generation chair).
  • As a final form around which various upholstered designs could be generated (Knoll Eames or Herman Miller ranges)
  • As a final form around which other associated furniture or workstation accessories can be generated (modular office systems)
  • Consider Gordon Murray’s system consisting of tubes + composite giving extra strength  (Note by Peter Bessey )


Largely determined  by the the head-rest and foot-rest. Also ? size models.   See .    In spite of all their adjustments, bells and whistles, Hermann Miller still has 3 sizes.   We should follow with something similar.

Pelvic (Iliac) support 

Pelvic support was developed by John Gorman an engineer and chiropractor was in contradistinction to the prevailing ‘lumbar support’.  Precise support, shaped to the curve of the iliac crest is  applied to the posterior iliac spine and iliac crest of the pelvis.   A slight forward nudge at this point is mechanically efficient in extending the two lowest joints and prevents the pelvis rotating backwards.  Pelvic support was designed for upright chairs.   As a component of the cacass ‘shell’ it need only be minimal and not adjustable. Intended to prevent backward pelvic tilting when supine lying.  It cease to be ‘pelvic’ and becomes the adverse ‘lumbar’ support above 20 cm from the seat -pan.  Do not allow adjustment!   See 

Screen Shot 2017-05-09 at 17.12.05

Possible ‘wobble’ arrangement for the Iliac support section

  1. Midline fixing
  2. Main supporting skeleton
  3. Spring/rubber/sponge to allow movement as shown by arrows.

ANGLES & Backrest variability

CAD drawings suggest that the backrest should be hinged to the seat pan to obtain optimal configuration in the 2 modes.    Adds to manufacturing cost.These were explored by Peter Bessey as a theoretical exercise in 3D CAD, based on anthropometric (US) data from the well known Henry Dreyfuss book. It commenced around a simple 50percentile male mannequin which was readily available.  The information from this investigation, should first be used to generate a totally adjustable Rig device, that should be used for trialling and true research purposes, before any final design concepts are prepared.


With the adoption of the 4M deskless, work-station model the constaints imposed by these angles become largely irrelevant   See

The seat

2 holes should be cut near back of wood base to limit slippage with a FTS seat.  Position showed by Okamura research (below).

2T reclnd

“stool height.” The term “sitting height” is reserved for the height to the top of the head when seated. For men, the median popliteal height is 16.3 inches and for American women it is 15.0 inches. The popliteal height, after adjusting for heels, clothing and other issues is used to determine the height of the chair seat. Mass produced chairs are typically 17 inches high.

For someone seated, the buttock popliteal length is the horizontal distance from the back most part of the buttocks to the back of the lower leg. This anthropometric measurement is used to determine the seat depth. Mass Mandal seaproduced chairs are typically 15-17 inches deep.

The Seat height based on Mandal’s ‘Forward tilted seat’ (FTS).  Forward tilt down by 15-20°.

Peripheral details


It is suggested that the head support should be directed to the base of the skull in the simple office form.  Measurements are shown below.
Head-restThe head-rest should be adjustable in both

  • Longitudinal
  • A-P directions

Hd support2

Head suprt





Optional only if the heels do not rest on the floor or desk bar. This can be arranged if the chair is lowered when in the reclined mode (as in the Okamura chair).  I regard this as only acceptable if performed easily without complicated manual adjustments.  ( Is it possible to have a mechanism that does this when the user leans backward into the reclined mode?)   A SPRUNG SOLE MUST BE OPAQUE FOR ISLAMIC SUSCEPTIBILITIES.

Screen Shot 2013-09-19 at 17.01.57A monococque design is probably unsuitable for an office work chair, but may be possible in a deskless design.  Ideally the leg/f00t-rest should retract or fold back when in the upright mode. A simple system is shown in the garden chair. A similar model can be bought cheaply at B&Q.

There is no need for the calf support.  This could result in DVT. The lower leg bones (tibia& fibula) give the only support required between  the thigh at the seat pan and the heel at the foot-rest,   However variability of the leg-support is essential and adjustment can be achieved by a telescopic spring arrangement extended by the user in the reclined mode but  retracts and folds back in the upright mode.

foot-rest Close to the Aaron concept

Aaron 2T chair

Hospital applications

I was warned by Cambridge to avoid discussion of medical applications of the 2T concept as this might detract from it’s major office use.

There seem to be 3 areas :-

  1. Mass emergency.  With the distressingly increasing frquency of international outrages which involve high volume of casualties which are tended while lying on the floor, a light emergency bed is required.
  2. Hospital special needs.  A 2T bed has a perfect application in a resuscitation unit.
  3. For specific hospital requirments such as neck traction.

A lightweight bed for emergency use.

A design similar to the p/1 prototype monocoque version is suggested.

Screen Shot 2017-04-12 at 17.15.19

The 2T principle Prototype p/1 has to be modified to allow stable positions in the transitional mode, contrary to the 2T principle 8.

Screen Shot 2017-04-12 at 17.21.51

  • Manufacture can be inexpensive.
  • For storage and logistics it can be easily disassembled and stacked.

The patient can be effortlessly put in the Trendelenburg position, can lie comfortably supported when lying  supine and can be in a sitting position.

Screen Shot 2017-04-12 at 17.26.57

Lying on side, prone or in the recovery position is possible.  The slight ‘iliac’ support would be lying above the pelvic brim and limit slippage if the head end is lowered.  The slightly elevated legs aids venous return.    It can be addressed by increasing the seat/back-rest angle or having these components hinged (an added expense).

Screen Shot 2017-04-13 at 16.25.44


.Hospital resus

A similar model to the above but of more robust design.  The ability to attend to the patient at a desired height and tilt is an advantage.  Rapid position change, particularly the Trendelenberg position, needed quickly in acute episodes, is a major advantage.


Hospital special needs

Cervical traction.  At present the patient lies supine and flat with traction from the skull to a weight attached over the end of the bed.  This is  prolonged and the position becomes uncomfortable, the constraint is a disadvantage and reading is difficult.   With a 2T design the patient can be tilted to a more comfortable, less constrained, semi-reclined position without altering the traction.

c tr2

Aetiology of LBP.

LBP. Cause (Aetiology).

The causes of LBP are multifactorial  and ill understood.    It is suggested (Adam et al.2002)  that  there is a need to integrate the evidence from genetics, biomechanics, biochemistry, cell biology and psychology to construct a comprehensive model.

Twin studies suggest that only 70% of the UK population is liable to LBP (Spector 1999). Other twin studies strongly emphasise the genetic factor in the aetiology of LBP  (Battie et al., 2002).   Genetics are not a cause of LBP but a risk factor acting through, possibly, spinal configuration or components of the disc composition.

Psycho-social factors, regarded as an important in the large increase in the last 20 years (Waddell 1996), is  more a response rather than a cause, resulting increases reporting.     Anecdotal evidence from patients with chronic LBP should not be ignored.  Although usually unaware of any causative incident, they are fully aware of what makes their symptoms better or worse.

The prevalence and incidence of LBP in populations that do not use Western style upright chairs but other ‘natural’ styles of sitting. which are culturally determined, is very low or nil, suggesting an adverse effect of the use of Western style upright chairs.    In Japan, this increases as elements of the population adopt Western chairs (Schlemper 1987).

Nutrition, environment and lifestyle may all play a part in the aetiology of LBP, but the only new factors that might account for the present epidemic is lack of exercise and a sedentary Western lifestyle.    Driving, office work, computers and TV,  the modern worker spends an increasing amount of time in a chair.

Epidemiological studies of  backache prevalence.

The literature on epidemiological evidence is extensive but, in relation to aetiology, confusing due to uncertainties and imprecision in describing reliably the condition that is under review.  Low back ‘trouble’ extends from LBP of psycho-genic origin to a midline IVD protrusion causing a corda equina syndrome, which is a surgical emergency.  Meta-analysis of systematic reviews, useful for evidence based therapeutics, have to be viewed with caution in extrapolating to clinical conditions. (Furfan et al 2001).  I have often seen wrong conclusions in my own field.

A study by the US Department of Health and Human Resources (NIOSH 1997) reviewed a number of factors and the general conclusions seem to suggest that the evidence was contradictory and confusing. There was an emphasis on non-physical psycho-social factors and heavy load handling.   Much of the research into the causation of spinal breakdown has concentrated on violent or inappropriate spinal usage afflicting manual workers today and hominins in prehistory (See Origins of lumbar vulnerability→).

In a Swedish review (Linton, van Tulder.2001) of controlled trials of preventive interventions for back pain problems only exercise gave evidence of relatively moderate significance perhaps suggesting that sitting has no influence on LBP.   The divergence of the  clinical and other evidence from that of some epidemiological studies suggests that the methodology of the latter should be reassessed rather than an immediate conclusion that seating plays no part in the symptomatology of LBP.

Invisibility is possibly due to  the universality of the upright sitting posture on chairs becoming  a part of the human condition in Western orientated populations, so that it fails to become apparent to recognition in systematic reviews.  This impacts on research, where musculo-skeletal funding is minuscule, in spite of the economic, which is about £13billion annually in the UK, and personal cost .

VR and sitting

Global blue chip companies are throwing their weight into VR development (hardware and software),  Mark Zuckerberg believes “this kind of immersive, augmented reality will become a part of daily life for billions of people”.

Roto VR chair

Andrew Lockley (→   ) discussed this (3/o3/2017) with Eliott Myers from Roto VR, which is a small, innovative firm with designs on the related accessories market.  He claims that “Roto enhances the seated experience with haptic feedback so dramatically you feel like you’re really there, in another world. Once you’ve tried Roto, VR feels empty without it.  With Roto, you can add our Table accessory, so you can drive around 360 degrees with a steering wheel (and pedals). Roto also has “rumble shakers” which can be affixed to the underside and back of the chair for added sensations. It’s like 4D on steroids. Actually we should call it 360D!”

Sounds exciting!

But not if the chair is liable to induce backache (LBP) on prolonged use. Their picture (  ) shows an upright chair with their concomitant disadvantages and with it’s extra, probably excellent, VR additions.

A huge opportunity

VR and sitting, if prolonged, will be relevant to chair design. It would not be difficult to redesign this chair to take advantages of the 2T or 4M concepts and so correct it’s seemingly obvious, from the pictures,  ergonomic deficiencies  This would have the additional advantage that the firm would have the basis for an ergonomic optimised office work chair that would jump ahead of the field.

If you are in the mood have a look at ☛ →


Screen Shot 2017-03-07 at 17.59.30From Gorman JD. MA (Cantab.) (Mechanical Sciences) MI.Mech.E (Member of Institution of Mechanical Engineers). MMCA (Member of the McTimoney Chiropractic Association) on 7/March 2017.

Yes I agree that a typical office chair and the typical office chair slump is wrong. Certainly semi reclined  position is one solution. I have rather given up trying to predict how the sitting world (the world of Homo Sedens) will evolve. It is certainly slow in recognising the problem which would be the first step.   This chair looks to me like a cheap after-market car seat. The computer people probably have no interest in the chair/seat so gave it no thought so long as it looked fairly high tech.     john g.

Screen Shot 2017-03-07 at 17.59.30Reply from Dr HA Sanford MA MB BChir (Cantab) D Phys Med (Lond).

You are probably right.   Then, I am not an expert on car seating like yourself.   Henry

Screen Shot 2017-03-07 at 17.59.30Comment from Dr HA Sanford

Virtual Reality (VR) is taking me back to ‘The Brave New World’ of Aldous Huxley (1932) which I read at school.   He described a dystopic utopian hierarchical society that kept control with consumerism, drugs (Soma) and VR (Feelies).  Work was done by robots and everyone was free to relax and enjoy promiscuous sex. Sounds similar to what may happen now.

This work was superceded by ‘1984′ by George Orwell, who was at my Prep school some 20 years before me, and hated it.  We all did but did not go into print so viciously.  ’1984’ faced the more immediate threat of Marxism which has now intellectually collapsed due to it’s internal contradictions and misunderstanding of the human condition.   So we are now back with ‘Brave New World’.   It does not sound too bad but actually is a form of slavery.  Those who objected, wanting to think, were regarded as barbarians and exiled.    To Iceland (as far as I can remember).  I used to run an annual course there (See the photographs in HOW WE SIT NOW→.)  The people are wonderful and it is very pleasant (in summer).

So, VR, here we come!    HAS

The end of sitting?

Sitting Is Deadly. Could Banning Chairs Help?

Peter Bessey (he did the CADs for me) sent me this link,

My initial reaction was that this was way OTT.  On second thoughts I realised that I had been saying something similar since 1998. As a consultant in Muscle-skeletal (Orthopaedic) medicine my interest was to remediate the factors that could lead to spinal breakdown.  Later, my general medical practice long past, I realised that there were also general medical adverse, potentially terminal,  effects.  It was mentioned under ‘Sitting Disease’ in    Chair DESIGNERS & Low Lumbar Backache

My own view is that sitting at work is not dead but should be transformed into a workstation incorporating the 2T (or 4M) concept.   HAS 18/2/2017.

I append a summary of the work by RAAAF

The End of Sitting 

This is an installation by the interdisciplinary Dutch studio RAAAF (Rietveld Architecture-Art-Affordances) and lies at the crossroads of architecture, visual art and philosophy.   In our society almost the entirety of our surroundings have been designed for sitting.  Evidence from medical research suggests that prolonged sitting results in serious health deficits.   These are so widely studied and well-documented that they’re impossible to ignore and show that sitting increases lower back pain, slows our metabolisms, and shortens our life-spans, amongst other things. Not even daily exercise is enough to offset the damage.

Redesigning the workplace environment and home might manipulate an impact on sedentary behavior.  Their installations are mostly conceptual.  But they bring up an interesting idea: What if chairs were eliminated altogether? Is that even possible? And would that solve work and societal sitting problems or just open up the door to new problems?

The RAAAF installations The End of Sitting, which debuted in 2014, and Breaking Habits, opening at the Mondriaan Fund for Visual Arts in Amsterdam February 16, present chair-free environments that encourage people to get up and move. As Erik Rietveld puts it, “As long as there are chairs present, people will sit in them habitually.”

The End of Sitting – Cut Out marks the beginning of an experimental trial phase, exploring the possibilities for a radical change in the way we work in 2025. This project is a follow-up of theScreen Shot 2017-02-20 at 18.47.09 architectural art instalation made in Looiersgracht 60, Amsterdam by RAAAF. It is cut out of the landscape of standing affordances and includes the most successful positions for supported standing. It allows visitors to stand, lean, hang or lay down while interacting, reading or working. The visitor is both participant and spectator. This travelling exhibition allows everyone to experience the future of the standing office.

Slideshow Credits: 01 / Photo: Jan Kempenaers via RAAAF; 02 / Photo: Jan Kempenaers via RAAAF; 03 / Photo: Jan Kempenaers via RAAAF; 04 / Photo: Ricky Rijkenberg via RAAAF; 05 /Photo: Ricky Rijkenberg via RAAAF;

Validating the science

Validating the science.  A Validated Biomechanical Model of Seated Postures

by David H. Wickett,1,3 Howard J. Hillstrom,2 and Rajshree Mootanah1,2

Medical Engineering Research Group, Faculty of Science and Technology, Anglia Ruskin University, Chelmsford, UK
Leon Root, M.D. Motion Analysis Laboratory, Hospital for Special Surgery, New York, USA DavidHugh Ltd, Cambridge, UK

Funding: This research was partially funded by The Kirton Healthcare Group Ltd, Anglia Ruskin University, and The Department of Trade and Industry
Conflict of Interest Disclosure: None
Correspondence Address: Dr David Wickett, DavidHugh Ltd, Unit D South Cambridge Business Park, Babraham Road, Sawston, Cambridge CB22 3JH, UK.

Running Title: A Biomechanical Model of Seated PosturesAbstract

Scratch references

Bogduk N, Macintosh JE. The applied anatomy of the thoracolumbar fascia. 1984; Spine 9: 164-170.

Bogduk N, Macintosh JE, Pearcy MJ. A universal model of the lumbar back muscles in the standing position. 1992; Spine 17: 897-913

Bogduk N. Clinical anatomy of the lumbar spine. 1997; 3rd Ed. Churchill Livingstone, Edinburgh

Gracevetsky S, Farfan H, Helleur C. The abdominal mechanism. 1985; Spine 10: 317-324.

Granata KP. Marras WS. Cost-benefit of muscle cocontraction against protecting against spinal instability. 2000;

Kamali N. Evaluation of total and semental lumbar lordosis using radiographic interpretation. 2003; Babol Quarterly Journal Volum 5 , Number 3:

Hides JA, Stokes MD, Saide M, Jull GA, Cooper ID. Evidence of lumbar multifidus muscle wasting ipselateral to symptoms in patients with acute/subacute low back pain. 1994; Spine;19.165-

Hides JA, Richardson CA & Jull GA. Multifidus recovery is not automatic following resolution of acute  first episode low back pain. 1996;Spine

Johansson H et al. A sensory role for the cruciate ligaments. 1991;Clinical orthopaedic and related research.268.161-178.

Saal JA & Saal JS.   Nonoperative treatment of herniated lumbar intervertebral discs with radiculopathy. An outcome study. 1989;Spine:14,431-437.

Wilke, H.-J., Wolf, S., Claes, L. E., Arand, M., Wiesend, A. Stability increase of the lumbar spine with different muscle groups.- A biomechanicaJ in vitro study. 1995 Spine 20, 192-198.


Cavanaugh, Kallakuri, and Ozaktay. Lumbar facet pain:biomechanics, neuroanatomy and neurophysiology.  1996;J Biomech 29: 1117-1129

Schwarzer AC, Aprill CN, and Bogduk N. The sacroiliac joint in chronic low back pain.1995; Spine 20:31-37.


Wilke H-J, Neef P,  Caimi M, Hoogland T,  Lutz E.  New In Vivo Measurements of Pressures in the Intervertebral Disc in Daily Life1999; SPINE Volume 24: 755–762

Adams MA, Hutton WC. The effect of posture on the fluid content of lumbar intervertebral discs. 1983;Spine 8:665-671

Aaras, A, Horgen, G., and Ro, O. (2000) Work with Visual Display Unit: Health consequences. International J Human-Computer Interaction. 12(1) 107-134.

Lueder R. Anatomical, physiological and health Considerations relevant to the SwingSeat. 2002; Ergonomics Review.

Gorman JD. The cause of Lumbar Back Pain; Eversley, England, Gorman, 1983. Ibid pp 95-106



29 Jayson MIV. Herbert CM. Barks JS.Intervertebral disc: Morphology and bursting pressure. 1975: Ann Rheum Dis 32:308-315.

30 Hutton WC, Adams MA. Can the lumbar spine be crushed by heavy lifting?. 1982; 7: 586-90.

31 Nachemson A. Morris JM. In vivo measurements of intradiscal pressure. J Bone Joint Surg (Am) 1964;46:1077.)

33 Nachemson, A. L., Disc pressure measurements. 1981; Spine, 6:93-97

34 Sato, K., Kikuchi, S., and Yonezawa, T. In vivo intradiscal pressure measurement in healthy individuals and in patients with ongoing back problems. 1999; Spine, 24(23):2468- 2474.,

35 Wilke H-J, Neef P,  Caimi M, Hoogland T,  Lutz E.  New In Vivo Measurements of Pressures in the Intervertebral Disc in Daily Life. 1999; SPINE 24, pp 755–762

37 Adams M, McNally D, Chinn H et al. Posture and compressive strength of the lumbar spine. 1994; Clin biomech 9:5-14

38 Wilke, H.-J., Wolf, S., Claes, L. E., Arand, M., Wiesend, A. Stability increase of the lumbar spine with different muscle groups.- A biomechanicaJ in vitro study. 1995 Spine 20, 192-198.


68 Nachemson A. Morris JM. In vivo measurements of intradiscal pressure. 1964; J Bone Joint Surg (Am);46:1077.

74 Sato, K., Kikuchi, S., and Yonezawa, T. In vivo intradiscal pressure measurement in healthy individuals and in patients with ongoing back problems. 1999; Spine, 24(23):2468- 2474.

89 Wilke H.-J,  Neef P, Hinz B, Seidel H, Claes L.  Intradiscal pressure together with anthropometric data ± a data set for the validation of model. 2001 Clinical Biomechanics 16 Suppl; 1: 111-126


4 Croft PR, Papageorgiou AC, Thomas E et al. Short term physical risk factors  for new episodes of low back pain.  Prospective evidence from the South Manchester Back Pain Study. 1999; Spine 24: 1556-1561.

3 Croft PR et al. Outcome of low back pain in general practice: a prospective study. 1998; BMJ 316: 1356-9.

98 Linton SJ, van Tulder MWPreventive interventions for back and neck pain problems: what is the evidence?   2001 Spine  1;26(7):778-87..

151 Patel A.  Am J Epidem;172:419, Quoted in New Scientist 29/6/2013:45

39 Hides JA, Richardson CA & Jull GA. Multifidus recovery is not automatic following resolution of acute  first episode low back pain. 1996;Spine