Category Archives: THE WAY WE SIT NOW

A look at the way people actually sit.

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 (→ https://www.exponentialinvestor.com/author/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 ( http://www.rotovr.com  ) 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 ☛ →

Comment

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

Art, Elegance and Objects of Desire

Aesthetics are hardly the subject matter of bio-mechanics and is left to the individual designer and Altmarkthe company image.   However there is relevance to chair design and furniture seen as art.   My apologies for this effusion which was occasioned by seeing,  in 2015, a new chair proposed by Altwork (http://altwork.com). that has at least an upright Screen Shot 2015-11-06 at 18.21.33and reclined work position as I first proposed back in 1998.  It also has a ‘stand’ facility so in this respect is approaching the 2T derivative, the 4M OFFICE WORK-STATION. I have not seen this chair and so cannot assess the extent to which it is 2T compliant.    From the photographs there seem to be problems.  It looks over engineered, awkward  and clunky.   See the Cambridge student model which does the same thing and is simpler and cheap

2T Deskless office chair SS prototypeThe model shown was an upgrade of my P1 prototype.   It was of this that a CEO said “This is too comfortable.   My work-force will go to sleep” although he was lying on wood Screen Shot 2016-06-06 at 17.45.21with no upholstery’  (Early 2Tilt chair CONCEPT and criticism→).     It looks surprisingly similar to the Kragel’s Nap Chair which i.e. regarded as an art object and was shown by Jessi Reeves  in her first solo exhibition at the Bridget Donahue Gallery. nvc. in 2015.

Having been married to a highly innovative abstract artist,  http://www.vancaillieartist.co.uk→  I have views!   Back in the 1960’s some regarded me as one of the few in England who could asses the aesthetics of the avant garde at that time.  Abstract Expressionism. Matter Painting,Tubism (Mathieu), Tachism, Pop etc.   Alas! Now I am totally dated!  But reactions do not fade.  True art has an effect that distinguishes it and is always itself true.   “Truth is beauty.  Beauty is truth” said Keats.

The untruthfull in art such as propaganda was demanded of artists in Nazi Germany and Soviet Russia and their derivatives such as ‘Social Realism’.    A reasonably good English artist, Richard Hamilton, was persuaded by his ‘Ban the Bomb’ CND wife to depict Hugh Gaitskill as a Hitleresque monster.  Obviously untrue.  To my mind, it destroyed  his artistic integrity.  Artists, although maybe dissatisfied with a work, never produce a bad picture, even with scribbles on a napkin.  I have a Calder drawn around a wine stains on a catalogue of his work.  We can be moved by nostalgia.  This is something else.   Alfred Munnings was anti modern art but his portraits of beautiful women, beautifully turned out and mounted on beautiful horses are nostalgic of an age recently past.

True art can evoke excitement and a ‘prickling’ & tingling physiological effect now known as Autonomous Sensory Meridian Response (ASMR) in the presence of certain work.  This can occur with sophisticated connoisseurs, and equally the naive.     Robert Graves in his ‘White Goddess’ (1948 – The White Goddess : a Historical Grammar of Poetic Myth -London: Faber & Faber) describes this effect and attributed it to the true  measure of a poet to faithfulness in depicting the White Goddess, of ancient tradition who was worshipped under many titles and forms, whether nymph, mother or crone, of the early matriarchal societies, thus proving the truth and source of his or her mystical inspiration.   Matriarchy, to be overthrown by invading patriarchal Indo-europeans, may have never existed but these emotional and physiological effects can be observed in poetic, musical and visual art forms.  “All true art is sacred” replied my wife (vancaillieartist.)  when asked why one of her works , an abstract relief, could be regarded as religious, and was requested for the exhibition of sacred art at the Musée d’Art Modeme, Paris, “Art Sacrée”, 1965.

Screen Shot 2015-09-29 at 18.53.20For me, the most interesting exhibit at Olympia, 100% Design exhibition, 2015, was this incredibly engineered and simple construct by Danial Chow  →.  Of solid walnut “Brackets or bracings that conventionally structure the architecture are substituted by hidden beaming inserts, invisible from outside”. He also wrote to me “Thanks for all the input you inspired me.  I will begin paying attention such a new measure – pelvic support or pelvic stimulator in my future designs.  I speculate that the said may also help stimulate the central nerve of the user while sitting.   It could then be the “real” solution and a new era also revolutionary to long time siting/working.     I may consider adopting this to working chairs and lounge chairs.”       I do not know about “stimulate the central nerve of the user”.  Sounds exciting!    He later wrote  “I did more thinking.  I realised it is possible to incorporate pelvic supports at the two sides of the lower-back-rest.  Perhaps I can design and make a new lower-back-rest to test the effect.  By the way, did I explain about how I came up with the configuration – dimensions and angles?   I did a mockup with a range of different configurations.  I picked the set which comforts the user most.”

Danial Chow, not an expert on biomechanics, has certainly ‘got an eye’.  As does any true artist.   I hope I have not misled him on iliac support.  Designed for upright sitting  it is less important for a reclined mode.  It would still help somewhat and some contouring would look good.  (see,BACKRESTS. Pelvic support→)

Screen Shot 2018-06-09 at 12.04.05Similar, also aesthetically pleasing, in 2018, is a work in carbon fibre by ‘Essence of Strength’ .   It does not have any ‘Pelvic support’ .  Pads are supplied to correct this deficiency which should have been unnecessary with better design.   <https://www.essenceofstrength.co.uk/>.    Although not intended as a work chair, the ideal ergonomic shape should approximate to that of the 2T (3M) reclined mode.    The 2Tilt RECLINED MODE for fully safe sitting.

This may be relevant to Furniture as Art (FaA) where so much are just amusing nonsense which some may find desirable.  To be ‘true’ and excite ‘desire’ for the object it must have relevance to the human body that is going to use it.   This means bio-mechanics.   Preferably an understanding is the Wolfsonbest but  may also be achieved on a sub-concious level by an artist.   “It’s all in the eye” said my wife, explaining composition and the golden section.

Wolfson seems to me to be have serious intent and to be the classic in this genre.  Of course he does not read work on bio-mechanics and so was unaware that desks in offices are becoming to look Dickensian (4M OFFICE WORK-STATION)  But desks which are objects of desire will still be Wolfson deskused in private offices.

Screen Shot 2016-06-14 at 19.31.45

The observer or user decides whether the object is pleasurable, relevant and desirable.  The designer takes this into account. an ‘eye’ is a help even if the ergonomics are correct.

Without a nod towards biomechanics, some schools may be seen – dada, surrealism.

Screen Shot 2016-06-21 at 14.27.46 Screen Shot 2016-06-21 at 14.29.14 Screen Shot 2016-06-21 at 14.33.04 Screen Shot 2016-06-21 at 14.34.37 Screen Shot 2016-06-21 at 14.35.44

WHY? Mandal’s Homo sedens.

    The recommended ‘correct’ position was fundamentally wrong.  He  suggested  that   “Mankind has progressed from Homo sapiens to Homo sedens”.   AC Mandal was a leading Danish surgeon.  Becoming disillusioned in the conventional wisdom of the Screen Shot 2018-06-12 at 21.12.51principles of correct chair design, he transferred his scientific and critical training to that of the biomechanics of sitting.   He observed that young children naturally sit with the chair tilted forwards onto the front legs.    They then support their elbows on the table, which for a small child is the right height, and the protective lumbar lordosis is effortlessly and correctly maintained.   As the child grows the height of the table becomes  relatively lowered and the child then sits in the usual semi slumped position. This results in short episodes of backache, which are ignored, and possibly to permanent stretching of the posterior spinal elements which can predispose to instability and a lifetime of adult  spinal pathology.    ‘The Seated Man’119
Screen Shot 2015-11-27 at 13.36.05

Drawing on the work of Keegan120 in the USA, Schorbath121 in Germany and Akerblom122 in Sweden he concluded that children are instinctively right to modify their seats to tilt forward with a slope of 10 to 20°. This allows the hip angle to open from 90° to 120° and  the pelvis to rotate forwards, on it’s fulcrum at the ischial tuberosities, so that the lowest two lumbar joints are in the extended (safe, lordotic) position, ensuring the correct lordotic posture.  No back rest was necessary and the torso was free to move.

Screen Shot 2016-03-16 at 20.12.45The recommended ‘correct’ position was fundamentally wrong.   He wondered how such a poor position could have been accepted as correct.     He suggests that this posture was developed by taking a standing skeleton and sitting it on a chair.

 (The 4 (+2) main adverse effects apply :-

  • There is a x2.5 increase in spinal loading over full reclination on the discs and 40% over that of standing upright (Nachemson, Sato but not Wilke).
  • The pelvis tends to tilt backwards reducing the important and protective wedge (lordotic) angle at the lower 2 lumbar joints.
  • The position is prolonged in an office or work environment.
  • Lumbar (not pelvic)  support accentuates this effect.
  • And the hip flexion also tilts the pelvis backwards.
  • the vulnerable lower lumbar joints are forced into a flexed position so that the protective high wedge angle is reduced to a point that the disc contents are liable to move backwards and protrude.
  • A chapter in his book is titled ‘Functionalism’s instruments of torture’ and he dates the decline to the 1930 Exhibition in Stockholm which had the slogan “Beauty in everyday furniture”.   Later he met the authority who created this concept who admitted that the image of the back of a standing person was simply cut and pasted to a drawing of a sitting person (personal communication).  It has no scientific basis.  This basic false premise is still regarded as ‘correct’, regardless of more recent scientific knowledge of spinal pathology and bio-mechanics and is still universally advised with an air of authority.   Mandal claimed that 90% of lower back pain was related to loss of this lumbar lordosis.
  • With the increasing liability to backache, an ergonomically ‘correct’ chair was sought.
  • Wrongly!   ☛The upright seated posture.→ Screen Shot 2015-11-28 at 15.44.41
  • Screen Shot 2016-01-14 at 18.19.39       Google→ shows an amazing collection of diagrams and pictures of ‘correct’ seating with a few that are actually correct.   For a similar account see bodyzone  shops→
  • Screen Shot 2017-02-11 at 17.18.18
  • This mistaken view of correct seating is still accepted and widely promulgated by authorities who advise on such matters.
  • His proposed solution was a combination of height adjustable desking and forward tilted seat similar to the equestrian seat.FTS
  • And belew a typical example of an authoritative diagram, (one that we all, in the UK, know and love) that illustrates ‘correct’ seating posture.
  1. The head and neck are in a terrible position.     A ‘dowager’s hump’ is already appearing in the upper thoracic joints!  The artist is right, the concept is wrong!Badsit 2014-04-03 at 14.12.49
  2. And the small amount of back adjustment is irrelevant and is nearly always adjusted in the wrong direction.
  3. The back rest seems to be providing unsatisfactory lumbar support. A mid-upright chair of this sort requires iliac support.
  4. The upright position = high axial spinal loading.
  5. The hip joint is flexed to a right angle. This has the effect of tilting the pelvis backward.    A forward tilted seat would help.
  6. The conventionally recommended knee position is also a right angle. This is wrong as the knees should be moved for physiological well-being.
  7. In general, a foot rest is not desirabl as it limits leg movement.  However a ‘sprung’ footrest which exercises the calf muscles can be helpful and comforting.

Another diagram for correct seating actually spells out the arguably adverse ergonomic recommendations!  (outlined in red)

badsit5The lady is sitting  bolt upright, to attention, like a guardsman.  The body position shown is cramped and movement, which is necessary for comfort and disc nutrition, is hardly possible.

There is no armrest.  Some authorities maintain that this allows greater movement of the upper torso.  However support under the elbows prevents dropping of the shoulder girdle which can be tiring and uncomfortable.  Support at the wrists helps to prevent RSI.

The diagram shows the neck in the correct neutral position.  Unsupported cervical flexion results in much greater axial compression.  (This is equivalent to looking downwards when standing,  see Hansraj KK. 2014)

A greater viewing distance allows the intrinsic eye muscles to relax.   The rule should be to be as far from the screen as vision allows comfortably.  If necessary get glasses, tinted against glare, adjusted to 36 inches.

Screen Shot 2018-06-11 at 21.04.14This diagram might be acceptable, a semi-partial remediation, if the point was made that it incorporated the alternative ‘Pelvic (iliac) support’ instead of ‘lumbar support’ as is shown. This alternative solution of applying the support directly to the pelvic (iliac) crest, ensures that it was unable to rotate backwards. This support should be a particular shape and size to spread the pressure loading.  (See later under ☛ Pelvic & Lumbar support→).

There are now many well engineered and comfortable office chairs in the market.      Screen Shot 2016-02-14 at 18.18.00Most have a fundamental bio-mechanical fault.  They rely on the mid- upright mode of sitting for prolonged work.  As has been shown this combines the two most adverse effects although the backward pelvic tilt can be modified by a FTS or lumbar support. My own opinion on a number of top range chairs, as shown, is of admiration of the design and engineering  mixed with awareness that the most essential bio-mechanical points have yet to be fully appreciated.   The following are better than most as efforts have been made to incorporate pelvic support (with reservations).Chairs2014-04-03 at 14.10.35

 

Ergonomics-standard-diagramThe latest version of BS EN 527-1: 2011,(the European standard specified dimensions for office desks and tables.)  state that fixed height desks should be 740mm ± 20 mm and desks should adjust between 650mm and 850mm for sitting modes and between 650mm and 1250mm for sit/stand desks.

The suggestion of a FTS would have been helpful.

Next, see ☛ Various chairs. How do they measure up?

Screen Shot 2013-10-13 at 14.47.34

 

 

How other people sit

Better!   But not for office work.

Japan.

Screen Shot 2013-09-26 at 22.51.16The Japanese kneeling posture, like most things Japanese, is highly sophisticated.   It is elegant particularly when a Kimono is worn and for women the firm Obi also provides support.   The body weight rests on the heels of the extended feet so that the hips are extended at a slightly greater than a right angle. This allows the pelvis to rotate forwards, as with a forward tilted seat, resulting in  a lordosis at the lower lumbar joints.    The torso can remain comfortably upright as in the modern, forward tilted Scandinavian Balans chair.Screen Shot 2013-09-24 at 19.24.16

 

Screen Shot 2013-09-26 at 22.51.43The Japanese, like most people of the Far East, have hyper-mobile joints but the more hypo-mobile Europeans find this position uncomfortable to maintain as it requires extreme forced flexion of the knees and extension of the ankles.    Frequent and prolonged use of this position results in callus formation on the dorsum of the feet.

 

JapSit2

When I asked this Icelandic girl to sit to have her neck examined, she adopted the Japanese sitting posture on a chair.   When asked “Why?” she answered “Because this is the way  that I have been taught by my Physiotherapist.”  Note that her hips are extended to a near FTS extent.

The traditional Japanese sitting posture was shown in a study (Schlemper 1983) to cause less back problems than sitting in a chair but increased as upright Western seating was introduced.

Various sitting and standing postures were measured for degree of lordosis and electrical muscle activate (Dolan, Adams 1988).    The results confirmed that of the sitting postures, the Japanese involved the least flexion but the most muscle activity to maintain, whereas  slumped sitting on the floor  involved much greater lumbar flexion but very little more muscle activity than standing.

 The slumped and squatting positions are used by most non-Western peoples and who tend to have a low incidence of LBP (Fahrni  1965, Jonck 1961) , the wedge shape of the vulnerable lower two lumbar joints (L4/5 & L5/S1) is preserved although there is flexion throughout the lumbar spine  (Bruggeman 2000).   Intra-abdominal pressure maintained by the abdominal and spinal muscles acting through their flat tendons and fascia and the upper body weight is brought forward to lie over or in front of the abdominal cavity which can be regarded as a balloon or football,  This has a pressure relieving effect on the spine and transmits a proportion of the upper body-weight  directly to the pelvis.  Gorman has also pointed out, this position exerts traction on the lower two lumbar joints, so that although the joints are flexed the compressive force has been reduced.

To review the bio-mechanic problems that occur with sitting and their ☛Remediation⟶

Next, some side issues, ☛ Why?  Mandal explains⟶

HOW WE SIT NOW

How we sit now is badly!  The recommended ‘correct’ posture  being almost impossible to maintain, most of us sit in a posture that can be shown to invite spinal breakdown.

The photographs show a group of doctors and physiotherapists who are attending a course on orthopaedics.    Most are sitting slumped with rounded back. This allows the pelvis to tilt backwards and  stretches the posterior ligaments but is not as adverse as sitting bolt upright as currently advised and is nearly impossible to maintain.

WWSN1

 

WWSN.2

The chair seats are parallel to the floor so that an upright posture must entail flexion of the hips at a right angle.  Crossing of the legs accentuates this.    The lumbar lordosis is lost and a flexed position of the lumbar joints occurs which can be clearly seen.  Note that none is using the backrest except for the doctor in the white shirt  who is in a semi-reclined slouched position.  In this mode the lower lumbar joints may be unsupported and flexed (but see below) and the posterior ligaments are stretched but the intradiscal pressure is reduced from 0.44 MPa to 0.27 MP as shown in a study in Ulm by Wilke (Wilke 2001).  If fully supported this is moving towards the 2T (3M) concept of  a reclined work position and John Jukes commentated was commonly seen in offices (See Managing the Ergonomics in the office→).  WWSN.4

 The physiotherapist in the check shirt is sitting forward on his seat in order to extend his hips slightly.    The table is too low for him and so he loses this advantage as he has to  bend down towards the table top.  In Wilke’s study bending forward about 20° with straight back and without arm support increased the pressure to 0.63 MPa up to 0.83 MPa, which was reduced  to 0.43 MPa when the elbows were supported.   The physiotherapist in the striped shirt has adopted  an extended position as he is able to brace himself with his arms.  This has the added advantage of forward rotation of the pelvis and so protection of the disc wedge angle. A work position, of this sort, was found to be the commonest (52%) in the quick study (below).

WWSN.5

In the next picture I am seen using a stool shaped like a saddle.   My hips are extended but this advantage is lost as the table is too low.  A saddle seat becomes uncomfortable due to localised IT pressure. This happens less with the equestrian saddle due to movement.

 

A pilot study, in 2013, of how we sit now by students, at Cambridge, working on a project for a 2Tilt chair in relation to desk interface  and office space indicates results, from a nearby office, that might surprise some people.   This was occasioned by the somewhat confused results of intradiscal pressure studies where there is a variation in sitting positions and units used and is also relevant to the single pMRI study (Smith 2006).  A more complete study is required.Screen Shot 2013-09-24 at 19.25.36

In the absence of reclined work chairs only15% + 3% were sitting upright.

The slouch.

Another reprehensible posture –  or is it?

Screen Shot 2013-10-23 at 14.22.53The popular slouched or slumped posture when sitting in an upright chair looks very wrong if  the misconceived ‘correct’ sitting posture, as excoriated by Mandal, and confirmed by the correct ‘preserve the lumbar lordosis’ dictum is accepted,   It is assumed that this posture will cause LBP. This may be true for Western societies where children have been universally accustomed to sit in ergonomically unsuitable upright chairs. This is an oversimplification when non-western sitting is taken into account.

slouchThe diagram shows that the flexion occurs at the upper lumbar joints with normal, or increased up to 40°, kyphosis of the thoracic spine. The pelvis lies fully on the surface of the seat and cannot tilt backwards.  The two lower lumbar joints, where IV Disc derangement typically occurs,  are safe with the wedge angles preserved.   The position is not very different from that in a semi-reclined chair.   In the 2Tilt (3M) version emphasis is placed on correct support from head to feet, with a slight degree of iliac support to prevent sagging at the lumbo sacral junction.  Wilke  found the L4/5 intradiscal pressure to be 0.27 MPa against  0.45 to 0.50 MPa when sitting upright (Wilke 2001).

The modern epidemic of backache is associated with lack of exercise and, In spite of uncertain epidemiological  evidence, prolonged upright sitting in chairs.    This is a relatively modern habit.    High backed chairs were an article of state and dignity.    Even monarchs used their thrones for limited and specific events.  Most people sat or squatted on the floor in various ways, which were culturally determined, and  benches and stools were the ordinary seats of everyday life.   It was in the 16th c. that the chair ceased to be a privilege, and became a standard item of furniture for anyone who could afford to buy one and the chair speedily came into general use and that is how we sit now.

Joint stoolJoint stool. These were made in large quantities in the 16th and 17th centuries. They were the most common form of seating before chairs became universal.  Users tend to perch with hips extended as recommended by Mandal.  People did not seem to be bothered much by backache. They were erroneously called ‘coffin stools’ in the 19th century.    Shown are two late 17th c. models.

Next see ☛ How other people sit

And   ☛ Various chairs.  How do they measure up? →  

See also a lighthearted account of the Victorian office. which also includes an account and treatment of RSI (WRULD).