Familiarity bias is a factor in holding back the development of ergonomic seating.  Efforts at remediation of upright seating seem to have come to the end of the road. To address the epidemic of LBP a paradigm change is required.

‘Familiarity’, ‘Confirmatory’ and ‘Normalcy’ bias is recognised by Behavioural Psychologists as Cognitive dissonance, first described by Leon Festinger in 1957.   It  is the condition described  as the unease felt by people whose experience or information is inconsistent to other, usually already held, beliefs.  Information and situations are avoided  In an effort to reduce this discomfort and regain psychological consistency.   It can be a factor leading to serious, even catastrophic, situations.

The general familiarity bias ….

We are hardwired to believe the world we live in today and to which we are acclimatised so that we become incapable of comprehending and believing that change is coming.  In general most users have been commanded, since nursery days, to ’Sit up straight’ or worse ’Stop tilting your chair forward’, a normal response of a child to adopt an actual correct position.   Later  ‘expert’ advice on ‘correct’ sitting upright is given with authority.  This is inspite of having been demolished by AC Mandal back in 1985 (See→Why? Mandal’s Homo sedens. ).   This mistaken view of correct seating is still accepted and widely promulgated by authorities who advise on such matters.   

The bias holdup

Failure to understand familiarity bias I have found  pervasive among chair designers.  Peter Bessey comments in this work (→COMFORT)  “Introducing medical-based information to designers and their education, at an early stage in their careers, would be a good way to change the status quo. The question is: how do you get that over to them in a lucid and easily digested manner? It needs to be described and presented in an easily accessible manner and not necessarily couched purely in medico-scientific terminology.”  In other words, they are really not up to speed on the scientific evidence.

Normalcy bias is slightly different and can lead to serious problems for firms, however big.    It is a dangerous trap for manufacturers of ergonomic office chairs, who may be perfectly happy with the status quo, to fall into and it can blind recognition to a very real and credible threat.

People normally think that the experts are correct.  They have the top jobs and the top positions in the professions and universities, and so generally that’s true.  Until the next scientific advance arrives.  A scientist  at CERN explained “you know, so far my theory is safe, but it might – you know, ask me next week, they might have found out that I’ve been wrong my entire career”.   Good scientists are prepared to admit this but most people are overwhelmed by familiarity bias.

The Ptolemaic system of astronomy seemed to make sense of what was observed in the sky above, that the earth is the centre of the universe.  It worked for 1,500 years even becoming a tenet of Christianity, until Galileo made the mistake of inventing a telescope and Copernicus showed, scientifically, that it was wrong.  The Christian was an example of familiarity bias.  There’s now new research coming out on what’s called the double split experiment, which is a major contributor to the understanding we have of quantum mechanics, which is now maybe violating the popular interpretation of that, 70 or 80 years after it was made.  Change can be slow.  That misplaced advice on ‘correct’ sitting posture is an example.

It is not surprising that most people have difficulty in over-coming the ‘familiarity bias’ engendered.  The exception are many backache sufferers and the younger, millennial, generation who are capable of thinking ‘sideways’.

My own initial training in Biology has made me mistrust sudden jumps (large mutations) in ‘natural selection’ as these are usually deleterious. It is small incremental advances over time that result in progress.  The same can be applied to political ideology which has made me a conservative.  However when real scientific evidence advances it may be time to change.   The 2T or 4M concept, in terms of chair design is only an incremental change.  Most office chairs need only modifications.  But as a concept it seems to excite cognitive dissonance and be regarded as a ‘paradigm’ shift.

 Comment

From Prof. MC Boulter
The comments in your  interesting blog remind me of the theme that d’Arcy Thompson used to preach a century ago. He must have influenced you also.
Best wishes
– Michael

     Reply from Dr HA Sanford 

d’Arcy Thompson, I think, had a mathematical approach to development and did not understand evolution by natural selection, which is my approach.  I see the 2T concept as an incremental change, along the lines of development by natural selection.   In the world of chair design the 2T concept is perceived as a ‘paradigm change’, a reclined instead of an upright posture, and I have to accept that as being so and say so.   These alternate viewpoints may make my explanation sound contradictory and excite cognitive dissonance.

 Back-rests.  A partial solution only if correct.

Correct back-rests with pelvic support prevents the usual backward tilt of the pelvis which flattens the protective lumbar lordosis.   The emphasis is on ‘correct’.     Gorman JD, whose analysis is included, pointed out the importance of the positioning of the back-support and distinguished –    

• Pelvic (iliac) back-rests.  Of fundamental importance for any chair design intended for prolonged use.  Support is directed at the level of the pelvic Iliac crest, approximately 20 cm above the seat.
• Lumbar back-rests.   Support is directed to the lumber spine above the iliac crest.  it fails to prevent backward pelvic tilting and can be seriously adverse.

Pelvic tilting.  A result of upright sitting

The backward rotation of the pelvis when sitting results from the weight of the upper body acting down on it via the spine and has already been described in the post (Biomechanics/Effects on sitting
posture) and it’s effect of reducing the IVD wedge angle (Angles & lordosis).  AC Mandal described this change and how a misconceived lumbar backrest, that is intended to reproduce the lordotic curve which pertains while standing, was arrived at in the 1920’s.  It provided the theoretical basis for the adverse traditional ‘correct’ sitting posture. ☛ Why? Mandal’s homo sedans→ . It was reinforced when Cyriax¹²⁶ pointed out the importance of lordosis in avoiding retropulsion of the disc contents with his adage “Preserve the lumbar curve”.

Position of the back support

This is important.  The effectiveness of any upright chair in reducing LBP depends on the positioning of the back-rests.   The variation is surprisingly small.

Not all authorities agree on the terminology. Above is my own view. HAS.     

Relevance to the 2T (3, 4M) concept.  Back-rests incorporating Iliac support can be a component of a 2T chair both as a remedial component for the upright mode and also to prevent a backward tilt in the reclined mode.

Height adjustment?

Most work chairs have adjustment mechanisms that puts the support above 20 cm.  This is to accomodate the tall user.  This mistaken concept should be resisted and adjustments avoided.  If adjusted higher there is a potential to result in adverse effects for average users.. A tall person might lose some mechanical advantage but would not incur any harm. A chair designed for a large person can have the iliac support at a higher level (max 168 mm,) that would be adverse for a small person.

The height of the posterior superior iliac spine above a seat (ignoring interposed soft tissues] Is between 146 – 168 mm.   (Diag. by Wicketts D, 2014, after Reynolds)

 

 

 

Pelvic and Iliac support.  

 Pelvic support was developed by John Gorman an engineer and chiropractor (Gorman’s41) was in contradistinction to existing ‘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.This brings the iliac support round to encircle the entire Iliac crest, ie. half way round the lower torso.  This is certainly comfortable and gives maximum mechanical effectiveness.  However chair designers don’t like it as it looks “too like a hospital chair for the disabled”.

 

 A compromise is to direct the support to the posterior superior iliac spine (the back of the iliac crest).  This should be adequate to prevent the pelvis from tilting backwards but may be less comfortable.

Following the publication of Gorman’s ‘Pelvic Posture’ principle a number of other back-rests have been developed also called ‘pelvic support’.    Subsequent designers seem to have missed this point and allow pressure to be directed  to the L5 & S1 spinous processes in  the mid-line  which gives uncomfortable point pressure.  More correctly, this is ‘sacral support’.   In retrospect it was perhaps unfortunate that Gorman named this concept ‘Pelvic Support’ when more precisely it is Iliac support.    Pelvic support, of some sort, has increasingly become accepted into mainstream chair design. Even cheaper chairs tend to direct the support to the level of the iliac crests although Gorman’s work may not have been recognised and not fully implemented.

 Gorman’s analysis.  He wrote:-

“The theory of lumbar support is a simple mechanical error; the result of orthopaedic surgeons not having engineering knowledge and seat and chair engineers, no anatomical knowledge.

When we sit, the primary effect is the backward rolling of the pelvis, because all the leg muscles connect to the pelvis so, when the thigh goes from vertical to horizontal (or beyond) in sitting, the pelvis tends to roll back too. (Tight clothing accentuates this).  The weight of the upper body transfers down the spine, on to the back of the pelvis – rolling it backwards.  These two effects cannot be resisted by supporting the spine directly, and the result is maximum bending force where the spine connects to the pelvis. This is exactly what lumbar support causes.”        (John Gorman).

His mechanical analysis, showed that, in the sitting position, a support behind the lumbar joints results in flexion of the L5/S1 joint (X). This is the joint at which 80% of disc pathology occurs and flexion is precisely the position that has to be avoided, particularly if the wedge angle can fall below 0° (ie. vertebral joint surfaces parallel), which is usual in Western populations.   Schorberth¹³² showed that the pelvis rotates by 40° on changing from the standing to sitting mode with lordosis loss at the vulnerable L4/5 & L5/S1 joints.

The Gorman paradox. Support of the lumbar spine at the levels above the pelvis resulting in adverse flexion at the lowest 2 joints seems to be at variance with common experience and is difficult to understand.   The spine is generally conceived as a semi rigid column of chunky bones, equivalent to a  vertical flexible rod, so lumbar support seems reasonable.      However, the anatomical reality is that the lower end of the flexible rod is firmly embedded in a large solid chunk of material, the pelvis.  In this case the force directed at the rod will result in lordosis at its point of application but this changes to a position of flexion at the lowest one or two joints which are fixed to the relatively solid pelvis.

 Gorman’s calculations were unexpectedly and serendipitously confirmed by a study in Sweden, by Andersson (et al¹²⁹ ) to show the effect of spinal inclination on the lumbar joints in the upright sitting position.   A number of angles (see below) were measured radiographically while standing, and sitting with  various angles of backrest and various depths of lumbar supports at different levels.    Gorman took Andersson’s raw data and re-expressed them as follows:-

Difference, in degrees, of joint flexion/extension at various spinal levels and thickness of lumbar support (-2, 0, +2, +4 cms)

 

Gorman’s own account can be seen→

• Note that at +2  cm of lumbar support, in column 3, in spite of 3.5° of extension at L1, the important L5/S1 joint is pushed into 4.9° of flexion!
• Also, in row 2, that the +2 cm of lumbar support results in flexion of the L5/S1 joint even when compared to sitting with no support, described by Lueuder as “the worst possible position”.  The L5/S1 joint is only moved into extension when the lumbar support is 4 cm thick.  This amount is uncomfortable.
•   These points were not commented on by the authors but Gorman asserts that “these figures means that lumbar support is having exactly the opposite effect to that intended.” 
• More recently this view has been further confirmed by pMRI studies (Smith FE 2006¹³⁷).
• pMRI sagittal lumbar scan with lumbar (not pelvic) support

The upper lumbar joints are in extension and the disc contents are in a central position.

The more relevant lower two discs have reduced wedge angles and there is retropulsion of disc contents at L5/S1 which appear to be about to extrude.

This effect deserves further study.

 

 

 

Gorman wrote:- “If the backrest is flat or only gently curved -seen from above- then it will only contact the sacrum (at 10cm or so above hard surface) or the posterior iliac spines.This could still be pelvic support but much less effective because it is only half the height and therefore half the leverage or mechanical advantage. The 20 cm level at the back will indeed be the lumbar spine.”¹³         Gorman also wrote (13/3/20013). “One of the problems of making a backrest effective in an upright chair -and this applied to our pelvic support chairs too- is that most of the users don’t sit properly against the backrest. Just look around any office.   The only people sitting up straight with full contact with the backrest are those that already have a back problem !   Everyone else is more or less slumping. “

For Gorman’s view on origins of LBP→

 JD Gorman explains the difference in stresses of posterior elements which occur in Lumbar and Pelvic support.

Henry      See attached pic from my document at Naturaljointmobility. 

A. If this car seat incorporated Iliac support, then the compressive force in the L5/S disk would be a bit less than the 40kg weight of the whole of the upper body.

B. If a lumbar support seat, as shown, then the only thing that can resist the occurring backward rolling of the pelvis is a tension in the red ‘posterior elements’ thing, the supraspinous ligament, the fascia or muscles. Regardless of the contribution of each of these structures in resisting the backward rolling, their total tension must result in additional compression in the disc.  Very roughly, by simple mechanics, in this drawing, the compression will be an additional  80 kg or so , tripling the compressive force in the spine to 120kg (very rough calculation!!)

Incidentally this shows the agreement between us of preserving lumbar lordosis and against the standard office chair or car seat.   You see the compression in the disc as the problem and I see the tension in the “red” ligaments as the problem because it stretches them outside their natural range.    Regards,   John

Reply (From HAS)

John.      An interesting analysis.  I think we agree that the common pathway to IDD is increased intra-discal pressure and associated with reduction of the disc wedge angle.  Your analysis shows that lumbar support may increase the axial pressure in addition to allowing backward tilting of the pelvis and reduction of the wedge angle.   In popular parlance, a ‘double-whammy’.  This may account for the discrepancies in the findings of intra-discal pressure research where the precise support is not specified ( a vague photograph is inadequate).

In addition to the above you are also postulating malfunction due to ligament stretching and a muscle ‘over centred’ position.   I mention this in the post ‘Anatomy’/ligaments where CTD is mentioned.  Solomonov seems to be the expert here.  Yours,  Henry

Failure to understand the principles underlying Gorman’s “Pelvic Posture Principle” can easily lead to a muddle.   An example is that of Hermann Miller.

The late John Jukes, who was investigating the incidence level of musculo-skeletal symptoms in offices, told me that he suggested to that ‘pelvic support’ should be incorporated in their models but said this was ignored.  Perhaps annoyed by his rebuff by the firm, Jukes later wrote “Henry.  A large percentage of staff throw out the lumbar support bar because it is too hard and uncomfortable. They do have a pelvic support now. However it has the same problem in that the support is concentrated at the base of the spine and not the iliac crest.”  He later wrote “It now incorporates pelvic support and so can be regarded, with reservations, as offering a semi-partial solution to the problem of LBP”.

Back-rests now …

The Gorman design,  suggested to them by John Jukes in the first place might have saved HM and their clients, decades  of trouble.    Gorman’s “Pelvic Posture Principle” seems now to have been largely accepted by mainstream designers.   The underlying principles are hardly fully understood.   Adjustments allow the rest to be raised to become lumbar support.    ‘Familiarity bias‘  rears it’s ugly head preventing the substitution of anatomical design for ‘adjustments’.   Chairs are still being designed with lumbar support and I sat in one recently when dining with young relations.  The chairs, of transparent plastic, looked cool.   The only trouble was that they were excruciatingly uncomfortable because the back-rest was lumbar and not pelvic.

A recent (14/1/2019) advertisement & and advice.

Next, see the second remediation ☛  The FORWARD TILTED SEAT (FTS).→

Or skip to 2T CONCEPT a full solution→

A Partial solution.

The Ischial Off Load system consists of a convex chair seat.  This combines both a FTS and allows, at the back half, pelvic support.

Derived from https://www.chairoffice.co.uk/blog/the-ergonomics-of-a-chair-explained/

This illustration for an advertisment (but not my comments) seems to show an Ischial Off Load system.   The front half of the seat is tilted forward approximating to a FTS so that the upper body static load ‘Off Loads’ pressure from ischial tuberosities to the thighs when sitting forward  and, depending on the chair height, increases the hip angle.   The back half (BPS) tilts back by 18° and allows the torso to sink back against the ‘Lumbar’ support (One hopes that this is pelvic not lumbar support) and so some of the static load transfers from the ischium to the backrest.   The ischial tuberosities get wedged against the backward sloping part of the seat surface which prevents the normal tendency to slide forwards on the seat when the lumbar or pelvic support pushes forwards enough to be effective. This means that the support can be more effective and if low enough can be pelvic support even though it doesn’t come round the sides of the iliac crest as in the original Gorman model which was more comfortable, effective and had no need for adjustment.  This advantage is slight compared to that of a reclined mode.

In the Makhsous study (¹³⁵),  kinematic, force, EMG, and X-Ray data were collected at the lower lumbar spine and showed some reduction of intra-discal load compared to unsupported or sitting with a straight backrest.  An ‘Off Load’ system seems to be described although the term is not used.   In the design used, adjustments could be made in the back and ischial supports  A plethora of adjustments is confusing and can be adverse, in a work chair, if adjusted wrongly.  Ideally they should be avoided.

‘Off Load’ is perhaps an unfortunate term.   Off loading from the ischial tuberosities (ITs) is subsidiary
to the  extension of the hips due to the FTS effect and and pelvic support achieved by the back half of the seat.   I have noticed that users tend to take advantage of the FTS component and perch on the front edge.  It is still possible for the user to sit in the middle of the seat and so adopt the upright ‘worst possible position’.

Gorman, himself, has posted a comment, in his usual vigorous style, related to the backward component.

reply

From JD Gorman     24 August 2013 16:34
Re: ‘Off Loading’.
Reading through the Makhsous document, off loading seems to mean reducing the force supporting the body at the ischial tuberosities which must then be replaced by a force to take the weight on the thighs via the hip joint. Why this should be promoted as advantageous, I cant think. The ischial tuberosities have been the support point in sitting for 50 million years in the monkeys, the apes and all our bipedal ancestors.

I think the authors have misunderstood the mechanics of sitting with the rear part of the seat sloped backwards. On trying a similar chair, the curiously named DROOP SNOOT,  I found that the ischial tuberosities got wedged against the backward sloping part of the seat surface which stops the normal tendency to slide forwards on the seat when the lumbar or pelvic support pushes forwards.    This means that the lumbar support can be very effective and if low enough can be pelvic support even though it doesn’t come round the sides of the iliac crest (as in my original concept).

Those DROOP SNOOT chairs certainly worked for back sufferers in locating the pelvis but the forces were high which made them uncomfortable for prolonged sitting.   They sold in all the back shops about 20 years ago and I visited the manufacturers in High Wycombe.

As you say seats like the HM Aaron chair do the same to some extent but not as much as the solid seat of the droop snoot. If it fixes the pelvis and therefore eliminates the backward rolling then it will eliminate the bending force in the spine which normally stops the backward rolling which occurs with normal lumbar support. This would reduce intra-discal pressure because part of the pressure is the direct axial weight. The other part is due to the tension in ligaments, such as  the supraspinous. ie bending force in the spine will result in compression just as it does in lifting.     John

 

JD Gorman explains the difference in stresses of posterior elements which occur in Lumbar and Pelvic support.

Henry      See attached pic from my document at http://www.naturaljointmobility.info/Prosthetic%20supraspinous%20Ligament.htm

A. If this car seat incorporated Iliac support, then the compressive force in the L5/S disk would be a bit less than the 40kg weight of the whole of the upper body.

B. If a lumbar support seat, as shown, then the only thing that can resist the occurring backward rolling of the pelvis is a tension in the red ‘posterior elements’ thing, the supraspinous ligament, the fascia or muscles. Regardless of the contribution of each of these structures in resisting the backward rolling, their total tension must result in additional compression in the disc.                  Very roughly, by simple mechanics, in this drawing, the compression will be an additional  80 kg or so , tripling the compressive force in the spine to 120kg (very rough calculation!!)

Incidentally this shows the agreement between us of preserving lumbar lordosis and against the standard office chair or car seat.   You see the compression in the disc as the problem and I see the tension in the “red” ligaments as the problem because it stretches them outside their natural range.    Regards,   John

Reply (From HAS)

John.      An interesting analysis.  I think we agree that the common pathway to IDD is increased intra-discal pressure and associated with reduction of the disc wedge angle due to flexion of the lower lumbar joints.  Your analysis shows that lumbar support may increase the axial pressure in addition to allowing backward tilting of the pelvis and reduction of the wedge angle.   In popular parlance, a ‘double-whammy’.  This may account for the discrepancies in the findings of intra-discal pressure research where the precise support is not specified ( a vague photograph is inadequate).

In addition to the above you are also postulating malfunction due to ligament stretching and a muscle ‘over centred’ position.   I mention this in the post ‘Anatomy’/ligaments where CTD is mentioned.  Solomonov¹⁸ seems to be the expert here.  Yours,  Henry

Next ☛  Sit Stand & stools→

OVERVIEW.   The 2 TILT (or 3M) chair CONCEPT.

The concepts derived from the scientific evidence.  see ☛Biomechanics→ .   It  is the optimised default  against which the ergonomics of any chair can be assessed.    An essential standard for chair designers.

The identified  adverse bio-mechanical factors :-

•  Listed here are those requiring remediation to ensure a safe sitting position
• The intradiscal pressure (IDP) from spinal axial loading in the upright state.  ☛Loading→ Raised IDP has increasing effect with degeneration which occurs in most people and may start surprisingly early.  ☛Inter Vertebral Disc (IVD)→
• Additional mechanical factors, such as flexion and rotation are required for  disc prolapse to result.
• A kyphotic, flexed lumbar spinal position leading to stretching of the posterior elements and ☛CDT→.
• Reduction of the IV Disc wedge angle  (☛Sato 1999).
• The retroversion (backward tilt or to an an anatomist a ‘forward tilt’)  of the pelvis, which occurs on sitting upright, reduces or reverses the protective disc wedge angle.
• A hip angle of 90° which occurs with a seat parallel to the floor allowing the hip extensor muscles (hamstring & glutei) to rotate the pelvis so as to flatten the lumbar lordosis. Ideal angle of hip extension is 130° shown by pMRI (☛Smith 2006).
• A prolonged constrained posture.
• Sleeplessness. (For an account see ☛Metrojet→ )

These are described further under ☛ Remediation→.

Only a reclined posture, basic to the 2Tilt chair concept, can reduce all these and this must be the only logical system for a prolonged working position.   

‘Two Tilt, 2T,  So called as there are only 2 stable modes, each at either end of range. The unstable transition is also a mode with actual benefits and allows the concept to be renamed Tri-Modal concept (3M).  The addition of a standing mode creates a Quadri-Mode (4M) chair station with a Sit/Stand capability.   The 2T concept, in it’s early days being a paradigm shift, engendered ‘familiarity bias’ for designers.   This is now decreasing  ☛Uptake & implications→

Essential REQUIREMENTS for the 2Tilt concept.          

Principle 1

 

A Partial solution.

The Sit Stand concept  slowed following work showing less difference in sitting and standing intra-discal pressures than was first thought.  A comeback is occurring as field research has shown the importance of keeping staff exercised.   

Effect of axial loading  on IVD intra-discal pressure

Originally Nachemson and others showed that the standing position had a lower intradiscal pressure than upright sitting.  This suggested that incorporating sitting and standing, with a sit/stand desk, could be beneficial if designed into an office environment.
This concept  has slowed following later work (Wilke 1999) showing less difference in sitting and standing intra-discal pressures and the general recent ergonomic improvement of office chairs.

Effect of movement on the IV disc

The negative consequences of constrained sitting has been described by a number of authorities.  See ☛ Exercise & movement→.  It has been shown that disc nutrition depends on the pumping action of pressure changes due to changes of position and is probably important in avoiding later degenerative changes.  In the context of chair design, movement is comforting and avoids the adverse effects of a prolonged constrained static upright mode on general health (See (Lueder R 2002).

Variable standing may be ergonomically superior to the prolonged use of existing upright chairs.    See ☛ BIOMECHANICS that determine safe sitting→).      There may be situations where the concept is applicable and as the  importance of keeping staff exercised is increasingly recognised.   Relevant is an authorative report by The UK DoH (Dept. of Health, Dept of Children, Schools & Families.) on ‘Sedentary Behaviour and Obesity: Review of the Current Scientific Evidence’. → https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/213745/dh_128225.pdf

But, on the other hand, prolonged standing is tiring and affects venous return.   Most people prefer sitting, because it is energy efficient with less action by the Erector Spinae muscles than when standing.   Whether it can adversely affect body and cognitive abilities is uncertain as some research contrarily shows the opposite including a shorter time in performing a task, as might be expected.

A large numberof standing desks are being marketed.      Having spent many hours in operating theatres, I am perhaps somewhat biased against prolonged standing.    The design of recent showpiece offices emphasise large attractive space where staff can socialise, discus innovation and shown looking happy.   Being an indoor environment the adverse factors shown in  OFFICE HEALTH, Stress & Ergonomics cannot be ignored if optimum productivity is required.  Of fundamental importance.

Not all office work is suitable for a Sit/Stand system and prolonged sitting may be required.     A 2T (3M) chair is essential and preferably the 4M workstation.  2T CONCEPT a full solution→

 HAS

Sit-Stand.Com is official supplier to the Get Britain Standing campaign. For summary guidance please visit: Benefits of Standing   They say Sit-stand desks (commonly referred to as “standing desks”) are increasingly expected to become the norm in the near future. Already in Scandinavia 90% of office workers enjoy the health benefits of sit-stand desks largely driven by workplace health legislation.

For an example  by RAAAF (Rietveld Architecture-Art-Affordances) , See ☛ The end of sitting?  →

Office-based’ studies

The first known ‘office-based’ study in the Department of Clinical Sciences and Nutrition, at the University of Chester, Chester, UK, 2016,  compared two days of continuous monitored capillary blood glucose responses to sitting and standing in normally desk-based workers.  The results provided encouraging signs of attenuating post-prandial glycaemic excursion  and why avoiding continuous sitting at work could benefit cardio-metabolic health.  The following articles are referenced:-

1. Prologed standing is tiring and affects venous return and can adversely affect body and cognitive abilities. – Are Standing Desks The Biggest Sham Ever?→    Wilmot EG, Edwardson CL, Achana FA, et al. Sedentary time in adults and the association with diabetes, cardiovascular disease and death: systematic review and meta-analysis. Diabetologia 2012;55:2895–905.
2. Saunders TJ, Larouche R, Colley RC, et al. Acute sedentary behaviour and markers of cardiometabolic risk: a systematic review of intervention studies. J Nutr Metab 2012;2012:712435.
3. Gennuso KP, Gangnon RE, Matthews CE, et al. Sedentary behavior, physical activity, and markers of health in older adults. Med Sci Sports Exerc 2013;45:1493–500.
4. Leon-Munoz LM, Martinez-Gomez D, Balboa-Castillo T, et al. Continued sedentariness, change in sitting time, and mortality in older adults. Med Sci Sports Exerc 2013;45:1501–7.
5.  Levine JA, Schleusner SJ, Jensen MD. Energy expenditure of nonexercise activity. Am J Clin Nutr 2000;72:1451–4.
6.  Koepp GA, Manohar CU, McCrady-Spitzer SK, et al. Treadmill desks: a 1-year prospective trial. Obesity 2013;21:705–11.
7.  Peddie MC, Bone JL, Rehrer NJ, et al. Breaking prolonged sitting reduces postprandial glycemia in healthy, normal-weight adults: a randomized crossover trial. Am J Clin Nutr 2013;98:358–66.
8.  Pescatello LS, Arena R, Riebe D, et al. (Eds). ACSM’s Guidelines for exercise testing and prescription. Baltimore: Lippincott, Williams and Wilkins, 2013.
9.  Speck RM, Schmitz KH. Energy expenditure comparison: a pilot study of standing instead of sitting at work for obesity prevention. Prev Med 2011;52:283–4.
10.  Blaak EE, Antoine JM, Benton D, et al. Impact of postprandial glycaemia on health and prevention of disease. Obesity Rev 2012;13:923–84.
11.  Service FJ. Glucose variability. Diabetes 2013;62:1398–404.
12.  Satya Krishna SV, Kota SK, Modi KD. Glycemic variability: clinical implications. Indian J Endocrinol Metab 2013;17:611–19.   A number of bio-mechanically efficient stools have been produced which usually incorporate a FTS, contouring and sometimes iliac support.
13. Paul Matthews,  from Office Fitness Ltd.point out that sleeping burns 59 calories an hour, sitting about 60 calories and standing about 80 to 90 calories.    Office workforce should do low activity for  5 hours a day.
14. The Journal of Sports Medicine in 2015 published research suggesting standing for two hours spread out in a  typical working day.
15. The Mayo Clinic suggests getting up for 10 minutes out of every hour.

Offices could have standing as the default working option with seating as the alternate mode.  The 2T (4M version).takes an opposite but complementary approach with the reclined mode being the default and easy ability to stand subsidiary.

Sit/Stand desks

Offered by the Market is often little more than an upright office chair and a variable height table.   Improvements include  

For a more sophisticated solution, a ‘stand’ mode can  be incorporated into the a 3M ‘desk-less’ workstation which then becomes a 4M concept (and a ‘full’ solution ).  This extra mode results in the  first change since the inception of the 2T concept in 1998.   (See ☛workstations→).

Stools

☜ The Pesko ERGO FLEX M 1_1 also incorporates a ‘wobble”.

A recent, more complex example is the Freedman chair in which the 2 halves of the seat can move independently, intending to accommodate spinal irregularity (scoliosis) and pelvic side tilting.  The emphasis is on the FTS concept and movement.☟

The HiLo
by Box Clever 2016, an innovation agency led by industrial designers Bret Recor and Seth Murray for Knoll  Knoll produce a number of high end task chairs with semi-remediation such as pelvic support but have not yet made the jump into a fully remediated chair.

It seems to be an indoor version of the old ‘Shooting sticks’ that I used to use.  Very sensible. (→ https://www.knoll.com/search-results?searchtext=HiLo&parent=1347382605724 )

Sitpack ZEN

“the world’s most compact chair + perfect posture”  Telescopes down to a small tube and made of carbon fibre and looks good.   Another ‘Shooting stick’.  I have been sitting on these for most of my life and have to admit that they are tiring. I would not care to work with one all day but then it would ensure that I move around.   ( See ☛ Sitpack ZEN →)

 The exact converse system

is designed to get the user off the stool to make way for another user.   A good example is an expensive designer stool with 4 legs and painted black as used in Mac shops.  Being an enthusiastic  Mac user myself, I am only too familiar with these.  They have a round, horizontal seat without conturing which allows point pressure between the ischial tuberosities (ITs) and the hard surface.   They have a newer model which is ergonomically not much better.

Problems may arise for staff & users who have to sit on them for longer periods. The view is of myself but It can be seen repeated in some random shots of staff users.   In the unavoidable, high loaded, upright position, the pelvis tilts backwards due to  the horizontal surface of the stool seat.  This is augmented by leaning forward, but some slight positive effect may occur by taking weight on the arms.

A light hearted account of 19c office conditions is relevant here.

Next ☛ A FULL SOLUTION→

A Partial solution.

The forward tilted seat concept preserves lumbar spinal lordosis and allows freedom of movement.

As already described ☛ Why? Mandal’s Homo sedens workers in Scandinavia, advocated a seat that was tilted forward and down by 20-30° from the horizontal, allowing the hips to extend to 120-130˚ and the pelvis to tilt forward with the lower spinal joints adopting the correct, safe, lordotic posture.   No back rest was necessary and the torso was free to move.   The  unsupported spine may incur slightly greater intra-discal loading probably from muscle co-contraction which is tiring and makes the FTS unpopular.   Makhsous (Makhsous M. 2003), has shown that sitting on a horizontal surface involves lumbar flexion relative to standing and   has also shown that with seat angled down, weight is largely shifted to the proximal half of the thighs at 18°. This was also shown in previous work (Corlett, 1999, Eklund et al, 1982, Schoberth, 1978).  This is relevant for  it’s short use in a 3M chair.

The kneeling component of the Balans chair, shown, is to prevent forward slipping.  With a static FTS this tendency to slide forward is tiring to resist.  Alternative options are non-slip materials, memory (See ☛ 2T Upright mode→)
Mandal determined, by tilted incrementally the chair seat and work surface, that an optimal position resulted in a correct lumbo-sacral lordosis and hip extension. Most people with back pain will find this very comfortable, but for the first weeks you will only be able to sit like this for 5-10 minutes, because your back muscles need training.”  ☞ Mandal

See WHY? Mandal’s Homo sedens.→

 

In a later study, Mandal concluded that the table should be at least half the person’s height (80-90 cm for older pupils) and that the chair should be at least one-third the person’s height (50-60 cm for older pupils). . The tabletop should slope backward 10-15 deg.    The seat should be capable of sloping forward 10-15 deg.

The Edge Desk

A folding computer desk and chair designed to be stored anywhere.   Similar to the Balans but more convenient , folds and has a worktop.  the knee support looks more comfortable. (<https://www.cnet.com/news/the-edge-desk-is-a-portable-all-in-one-office/?ftag=CAD-04-10aae9d&bhid=21821882752016996385501688627261>}

The forward saddle seat

Available 2020.   An illustration from an advertisment explaining the concept for this seat, designed by David James France, an Australian chiropractor. https://www.kickstarter.com/projects/workhorsesaddlechair/workhorse-saddle-chairs-improve-your-posture-and-w?ref=pr.go2.fund&utm_medium=referral&utm_source=pr.go2.fund

The Ischial Off Load’ system

The Ischial Off Load’ system is a variant consisting of a convex chair seat so that the  front half of the seat is tilted forward approximating to a FTS.  It is now incorporated in several office chairs.  ☛ Ischial ‘off-load’ system→

• UPRIGHT MODE & TRANSITION for the 2Tilt concept→
• Next you can skip to 2T CONCEPT a full solution→