Category Archives: The 2T FULL SOLUTION

A paradigm change for prolonged sitting. A solution that avoids all the adverse factors that occur with seating.

WORK-CHAIRS, a new breed with a reclined mode.

From a wierd concept in 1998 to become disruptive in 2017?  As predicted  this is begining to emerge.  
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.  It should also increase productivity.

We see 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 work-chairs shown here are only semi-2T compliant and appear to ignore the science and are based on engineering.    They do not invite a great uptake, inspite of extensive PR.

  Okamura is a major Japanese company and produced the Atlas, a reclined work-chair that was ahead of the field in addressing the biomechanical factors that are necessary to okamura1avoid or limit  LBP.
“Looks familiar, Henry?” was the message from John Jukes about this chair.  Sure enough it showed the semi  reclined work position that I had been advocating since 1998 on the web.  .  It has been suggested that Okamura designers had seen my web page.  I doubt this as they had failed to apply the essential requirements need to make this a more user friendly, ergonomically optimised and cheaper Screen Shot 2013-10-23 at 14.05.33model.    Their Atlas model allows some insights into where their design went wrong in relation to the 2Tilt (2T) concept.

  • It has a reasonably good reclined position.  But then things become complicated as it differs from a chair designed along 2T principles.
  • Problems occur with the further design and is unintentionally shown in the photograph, above, as the users head is not being supported.   This illustrates the point that adjustments are usually maladjusted and have confusing controls.

Screen Shot 2014-02-13 at 19.22.28

  • 1. Good.  Easily adjusted .  One of the requirements for the 2Tilt concept for users of differing height.
  • 2. Pelvic support should  be fixed at 200 mm.  (See BACKRESTS. Pelvic support v. Lumbar.→
  • 3. Also no need for this adjustment or for the depth of the seat.
  • 4. In the reclined mode the head-rest needs to be at about 6″ forward.
  • 5.  Good.  The reclined back-rest angle is 45°.   Better at 40° or less.
  • 6.  Good.  The backward extended legs give greater stability in the reclined mode.
  • Some adjustments should be avoided.  (See ADJUSTMENTS?→ )
  • The default upright mode is in the usual adverse mid-upright position.  (The upright seated posture.→ )
  •  I found the shift from the reclined mode to be awkward due to adjustments.
  • The 2T concept allows intermediate positions but these are unstable and can allow rocking exercise. (The unstable TRANSITIONAL MODE. It’s importance.↔ )
  • The seat is convex and can allow the user to sit back and take advantage of the pelvic (‘iliac’) support. In this case the headrest has to be adjusted back from it’s position that is required when reclined.   (see •3 above) (See‘Ischial Off Load system’).
  • The user can also sit on the front edge where the seat is tilting downward as with a FTS. Slipping could be a problem.
  • Fixed at a low level,  the seat allows the feet to rest on the floor in the reclined mode, as shown.  I am told that this causes problems for tall people who have tried it and an adjustable work-table may be required (no bad thing).
  • OKAMURA CONTESSADesigned and engineered to a high standard of sophistication but, again, there is a plethora of unnecessary adjustments with their controls which are so loved by contemporary designers.  Most  should be scrapped or disconnected by a user who is aware of the effect of adverse positions on spinal pathology.
  • The brochure states, ”The lumbar support gives you comfortable support.  You can adjust the lumbar support backward and forward up to 15 mm , and up and down to 60 mm.”   The upright work position shown is acceptable as the ‘lumbar’ is actually  ‘pelvic’ support provided it cannot be adjusted upwards above 20 cm.’.  Gorman  showed true ‘lumbar support‘,above 20 cm, to have the opposite effect to that desired and later confirmed by pMRI scans.
  • The reclined mode is about 50° from the floor, a little short of the ideal 45° but acceptable. The figure given above is 26° from the illustrated upright mode.  It relies on the ‘off-load’ domed seat.   I prefer the forward tilted seat (FTS) but know of no evidence that shows one system to be better than the

An object of desire?   Certainly not for me!   Even ignoring it’s shortcomings, I found it far too large and clunky.Screen Shot 2013-09-28 at 21.30.29
As predicted, a number of ‘work-chairs’ workstation type models are appearing which include a reclined work mode and so are superior to the present (2016) conventional upright models.  Appearing to ignore the science and based on engineering they do not invite a great uptake inspite of extensive PR.

The ALTWORK chair

AltmarkNow, in 2015, a chair is proposed, that has at least an upright and reclined work position.  However deficient in biomechanics (ergonomic) optimisation it may be, with reservations, it is  potentially the best work-chair in the market at that time. (     It also has a ‘stand’ facility so in this respect is approaching the 4M workstation→.    It incorporates iliac support (at least, I hope iliac and not lumbar), which is required in the upright mode but might be excessive for the reclined mode.  The reclined configuration can be deeply adverse as can be found in some dental reclined chairs.   There appears Screen Shot 2015-11-06 at 18.21.33to be intermediate  position adjustment in the transitional mode, which at best, gives no biomechanic advantage and was probably intended to add comfort → .   Misled by ” that treacherous guide  which only turns up truthfully when the ergonomics are fully correct”.   If this mode becomes a part of the unstable intermediate mode it allows a faster transition and also gives the user the choice for dynamic motion and rehabilitation.  A win-win.   Scrapping a fixed intermediate mode reduces manufacturing costs.    These faults could easily be corrected and so  with reservations, it is  potentially the best work-chair in the market.

Not having had an opportunity to see this chair, I cannot comment further on the ergonomics.   Expensive at $5,900,  it looks over engineered, awkward  and too clunky  for an ‘object of desire’.      ☛ Art, Elegance and Objects of Desire→    Did they arrive at this independently or did they see my web-page for the 2T concept? This has been in the public domain since 1998, later upgrade to the 3M (2T = 3M) & 4M   I fear it was the latter and the chance of a simpler, more ergonomically optimised and more elegant model was missed.  Also the aesthetics worried me.  I penned a hurried post on this subject.(ALTWORK & Art →)

Uptake and ‘Object of Desire’?

Appearing to ignore the science and based on engineering they do not appear to invite a great uptake inspite of extensive PR.

Screen Shot 2018-11-24 at 10.29.33Why?  Ignoring the the essential 2T requirements for an absence of adjustments and controls the models are clunky and not appealing.   The 2T simplicity reduces costs, improves function, improves ergonomics and enables a simpler and more elegant design.

For existing manufacturers this provides an opportunity and for any entering the field.   Top manufacturers are already recognising that they have come to the end of the line for ergonomics. Backache (LBP) and other spinal & muscle-skeletal conditions still persist resulting in stress and lowered productivity.   Will they grab this opportunity or be held back by Familiarity bias →?

Screen Shot 2013-12-31 at 12.36.29


Screen Shot 2016-06-24 at 12.34.17A good idea in that it achieves the 2 modes 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.      Price: $5995

Elecric mechanisms

The CHOTTOScreen Shot 2017-05-20 at 11.14.27

This highly innovative chair was introduced to me by it’s designer,Thomas Stroman.   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 one 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!  →​  and  The CHOTTO→

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.  This was evident to both staff and students,    The model demonstrated was a cannabalised version of the p1 prototype which had been formed from Electric tubular conduiting in the basement of the Cromwell Hospital with help from the electrician.

It excited comments  “Gee!    That’s cool.  I want it.”  so although simple it is an ‘An object of Desire’ at a student level.   Let us see what designers can do with the newer materials for the top end of the market.    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.   compare it’s simplicity with the next chairs.→

GTRACING Gaming Office Chair

Screen Shot 2018-06-21 at 14.26.06The ‘Game Racing Chair the top end of this version ($166), with a reclined mode and an upright mode with potential pelvic support, is coming Screen Shot 2018-06-21 at 14.26.37close to the 2T design concept but lacks simplicity and optimised functionality.   The ‘Ergonomic Backrest’, 
is spoilt by being adjustable. Pillows are OK but just not good design.    Recliner Swivel Rocker Headrest sounds good. .

Aircraft seating

Screen Shot 2019-03-15 at 16.42.26This seems to be always ahead of Office seating.   Benjamin Hubert of LAYER recently collaborated with Airbus to redesign economy class airline seating.   From the photographs this is hardly ergonomically impressive but the fabric claims interesting ‘all singing, all dancing properties’.   These include a knit seat cover with zones of various density that offer customized levels of support to the body and automatically adjust,  based on weight and movement. This is made possible by passing current through the conductive yarn to vary the seat tension.  The accompanying Move App, which when connected with the smart textiles gives users control over factors –like seat tension, temperature, pressure and movement. Presets include “massage”, “mealtime”, or “sleep”.     This may have ‘legs’, as a means to approach the 2T design concept, by reducing the overall complexity of seat construction, probably lowering cost of both seat and its tooling and by restraining overall weight, enabling a potential tilt mechanism to be less stressed and easier to control.  (Peter Bessey suggests)

How do concepts evolve?

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’.   Disruptive technologies have to prove themselves Screen Shot 2018-07-08 at 15.04.13first. 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.     So, work-stations have to use existing office spaces before becoming universal. (Dan DenningPublisher, Southbank Investment Research ).

Peter Bessey wrote (30/6/2016) “It has taken time for the market to build, but there is definitely a movement toward other postures in the workplace. While some of that has derived from posture investigation and potential for beneficial effects on the user, other advances have emerged as a response to changing technology, new materials and a non-paper work method, as seen from the 60’s onward.   I suspect that a NASA effect is involved in some of this too. Numerous resources have been directed into space travel in recent decades and, for human travellers, that has mostly incorporated a reclined support system to encourage stress-reduction during high-load take-off and landing. So there has been a real effort to ensure that anthropomorphic needs are addressed properly when working from that position, to ensure equipment control systems can be operated successfully and without long-term harm.   There have been a number of attempts to create pod-like structures around reclined positions, to create controlled environments for audio enjoyment, meditation and relaxation. Perhaps those too, have influenced the current trend? But the main factor may well just simply be the instant communication and data access that today’s world now has available for sharing ideas.  Apart from that, it is likely that this trend has derived from the typical and gradual process in which increased knowledge, enlarged awareness and advance in technology brings. Stale markets, where things have remained much the same for decades and highly competitive markets where a cycle of fashion and small detail differences are all the consumer sees on offer, can drive the introduction of disruptive design ideas and encourage new entrants to challenge the existing status quo. Perhaps that is what we are beginning to see    Best regards  Peter”

For further reading, see ☛

UPRIGHT MODE & TRANSITION for the 2Tilt concept

A 2Tilt concept Upright Mode is subsidiary but essential to allow the reclined mode to be fully and easily used in an office or work environment.   An unstable Transition Mode has health benefits and it’s importance is described.

Upright mode2T upright mode

The 2T upright mode is subsidiary but  required for certain short activities and quitting the chair and is the default mode when the chair is unoccupied.

The upright mode is for short tasks only and the configuration is unimportant providing that the intermediate, transitional range is unstable.

  1.  Maintaining the wedge angle of the lower two lumbar joints, in the upright mode, can be achieved by a ☛forward tilted seat (FTS)
  2. or by correct use of ☛ iliac support. The latter cause additional design problems in this case and so is not recommended for an original design but may be convenient for modification of an existing model.
  3. also see ☛the Ischial off load system→.

  An unstable transitional mode.

Easy transition (MSAS)

2T Principle 3.Requirement 8.  Mid ranges should be unstable and easily negotiated.  It is necessary to be able Screen Shot 2015-10-07 at 13.43.22to switch rapidly and easily from a reclined to the upright mode2T mid range.
  •  This is mainly for convenience but the switch also results in a change of pressure on the disc and this has the added advantage of providing a pumping action which aids disc nutrition.
  • Their instability  can be used for short periods as a form of exercise ( ☛dynamic seating→)
  • This is not just a quick transition from the reclined to the upright modes (2T) but the instability provides physiological benefits and is itself a mode.  The concept is renamed the Tr-Modal (3M).  2T = 3M.Screen Shot 2018-12-21 at 17.46.44

2Tilt Principle 3  Requirement 9. No adjustment is allowed to maintain an intermediate position. The adverse intermediate upright position should be unstable.  This allows an easy and rapid transition from one mode to the other and no adjustment is allowed to maintain an intermediate position.

Easy control free transition Camb

This may seem counter-intuitive.  Why shouldn’t the user be able to sit easily in any position that seems comfortable?   It worries chair designers dreadfully although they may not be bothered by the ‘dynamic seating’ concept..

Why?SS adverse upright sitting

  •  It is, equivalent to the mid upright position of most office chairs, carrying an ergonomic penalty.    A user, used to a mid-upright chair,  could use an adjustment to maintain this position for long periods which would add an unnecessary adverse effect to an otherwise optimal system.
  • The intermediate positions being unstable require muscular effort to be sustained.   On moving back a few degrees from the stable forward upright mode the occupant enters this upright unstable position which provides proprioceptive feedback and frequent small amplitude pressure changes. Sp movement
  • Spinal movement & change of position are important for a number of reasons including IV disc nutrition. ☛  Movement & exercise→
  • Particularly for rehabilitation of the Multifidus (☛ muscles→) following an internal derangement at the low lumbar joints.
  • A user has a choice and may find a short episode of this low amplitude exercise pleasant.  Longer periods are liable to be tiring.
  • There is also an added advantage  in providing therapeutic exercise following an acute LBP episode with it’s resultant muscle and reflex atrophy. (See ☛Anatomy/muscles).
  • Addition of a sit/stand mode in the 3M version allows the user to walk around.
  • ‘Dynamic Seating’.Recently there has been interest in continuous small amplitude movement for upright chairs, the chair re-aligning with the users centre of gravity.  ☛  Movement & exercise→
  • 2T exercise and movement systems   ☛  Movement & exercise→
  • Sit/Stand. Bio-mechanically superior to the use of existing upright chairs and can be an adjunct to the 2T system which then becomes a ☛ 4M work-station→ concept (and a ‘full’ solution).☛ Sit/Stand→

A specific illustration

AltmarkThe ALTMARK Chair has both a reclined and upright mode which makes it interesting and ahead of the market.   The webpage shows a fixed intermediate  position in both the reclined and semi upright modes.    At best it gives no biomechanic advantage and was probably intended to add comfort → .   Misled by ” that treacherous guide  which only turns up truthfully when the ergonomics are fully correct”.   If this mode becomes a part of the unstable intermediate mode it allows a faster transition and also gives the user the choice for dynamic motion and rehabilitation.  A win-win.   Scrapping a fixed intermediate mode reduces manufacturing costs. A win-win-win!   Further described in WORK-CHAIRS, a new breed with a reclined mode→.

Next, return to The 2Tilt RECLINED MODE for fully safe sitting. →  or check the effects of The upright seated posture. →


A quick overview



  • Why has it taken so long to design a chair that addresses all the factors that may account for backache (LBP) on prolonged sitting?
  • Is it that the full solution indicates a chair that looks too strange?
  • It suggests that office workers in the future may be in a reclined position most of the time or walking about.
  • This conclusion is derived from scientific work on :-

☛Spinal anatomy, ☛pathology & ☛paleoanthropology

☛Spinal biomechanics

and 50 years of experience

And has resulted in a 2Tilt chair solution

When first advanced 1n 1998 it was viewed with complete incomprehension by chair designers and manufacturers.  Now, in 2015,  they say “We agree,but ….” . Familiarity bias rules!

Once the main adverse effects of upright sitting are recognised then it becomes possible to consider the options available for remediation.   This is a resource for the design of chairs to avoid the associated LBP.   It should be an essential tool for any chair designer.

The adverse effects of upright sitting

sitting adverse effects

These adverse biomechanical factors  have to be addressed to ensure a sitting position that is the least likely to perpetuate, or result in, LBP and other symptoms.   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.

The 2 TILT chair CONCEPT.

The 2 Tilt (2T) chair concept is derived from the existing scientific work, already enumerated, to optimise the bio-mechanical spinal requirements  for prolonged sitting.

Screen Shot 2015-10-07 at 13.43.22•Biomechanics suggest that a correctly configured reclined, relaxed, mode is the optimum for prolonged sedentary work.  The 2T reclined mode→

•This requires a 2nd upright mode for certain short tasks.  Hence the 2T concept.    Upright modes→

•The intermediate positions should be unstable and easily negotiated.   The unstable intermediate mode→

This leads on to the 2T ‘deskless’ chair or work-station.


  • Reduced office footprint.
  • 2T requirements easier to achieve.

And some considerations :-

•☛ essential requirements →

•☛ Adjustments?

•☛ Comfort?→

•☛ Exercise & movement

•☛ 2T / Desk interface

•☛ 2T in the office →

•☛ Criticism →

RECAPITULATION & selling points

 A technical ‘fix’ is required if the increase in spinal morbidity and cost to industry of absenteeism and stress due to LBP is to be halted.

  • For a quick overview of the subject for non-specialists.
  • Western societies are unique in adopting, relatively recently (200 years), the mid-upright chair  for everyday sedentary work.
  • More recently there has been a reduction of exercise and horse-back riding.
  • The increase in Low Back Pain (LBP) has mirrored these changes.
  • This results in personal morbidity, loss of earnings and huge cost to industry.
  • The mid-upright sitting position details seem to have been codified in the 1920s as a result of a false premise (see the account of  Mandal AC. The Seated Man. Dafnia Publications. Denmark; 1985). It continues to be accepted as ‘correct’.
  • Recent scientific work on spinal pathology and biomechanics show that these ‘correct’ details are flawed and seriously adverse to spinal well being. Pressure studies of spinal loading show that upright sitting itself may be adverse. The mid-upright mode also carries other marked defects, such as backward tilting of the pelvis, which are accentuated if the 90° hip angle (seat parallel to floor) or if lumbar (as opposed to iliac) support is incorporated.
  • At present many work chairs can be unkindly designated as ‘Machines for making Backache’. A technical ‘fix’ is required if the increase in spinal morbidity, and cost to industry of absenteeism and stress due to LBP is to be halted.
  • The biomechanical imperatives show that a safe chair can easily be achieved with the ‘2 Tilt principle’.


Next ☛  →