Author Archives: Dr. Henry Sanford

About Dr. Henry Sanford

As a retired consultant in Orthopaedic (Musculo-skeletal) medicine, I was first trained in Orthopaedic Surgery and changed when working with JH Cyriax at St Thomas' Hospital, London, my old teaching hospital. He is regarded as the 'Father' of the subject. I worked as an Associate Consultant in the Rheumatology department, STH, in private practice in Harley St. and the Cromwell Hospital. I have run courses and lectured in in the UK, USA, Belgium, Germany, Scandinavia.

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. →

 

Sit/Stand & stools

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.

Screen Shot 2018-06-16 at 13.25.30

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. Ben Schiller 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  Screen Shot 2018-10-17 at 18.21.17

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

Screen Shot 2015-09-30 at 15.05.52

Screen Shot 2015-09-30 at 15.15.20☜ 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.☟

freedman-chair

Screen Shot 2017-02-20 at 18.22.18The 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 )

SitpacSitpack 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.  Photo on 06-01-2015 at 12.49Being 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.

Screen Shot 2015-01-20 at 12.27.40

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

Next ☛ A FULL SOLUTION→

The FORWARD TILTED SEAT (FTS).

A Partial solution.

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

Screen Shot 2018-09-22 at 15.05.21As 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.

Forward tilted seat

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 Screen Shot 2018-12-20 at 14.46.36(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.→

 

MandalIn 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.

Screen Shot 2018-06-27 at 18.32.39The 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

FTS Advertisment for 'saddle chair'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→

 

A quick overview

  

THE OPTIMUM SITTING POSITION FOR PROLONGED WORK.

  • 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.

Advantages

  • 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’.

See →

Next ☛  →

COMFORT

Evidence, for design, based on the perception of comfort, is biomechanically worthless.   Conversely a chair that has correct biomechanics is always comfortable.   Correct Biomechanics = Maximum Comfort.       Discomfort is probably a different modality and is significant.

Screen Shot 2018-09-23 at 12.08.55It is very understandable that the chair industry regards comfort as it’s ultimate aim. That is what the users want and that is what pays.  Discomfort indicates that something is wrong.. However design based on a search for maximising ‘comfort’ can be misleading.  It is a treacherous guide  which only turns up truthfully when the bio-mechanics (ergonomics) are fully correct.  The correct answer should be the Hippocratic ‘ ‘Do no harm'”

This can only be effected from medico-scientific design.   Observation confirms  the working assumption that an optimised configuration would inevitably ensure maximum comfort.

The Public judges a chair by it’s immediate comfort and intelligently ignores the ergonomic benefits described by the salesman.   I am told that this is not so in China where the health benefits are paramount.Screen Shot 2018-06-11 at 21.01.07

 

I had rather forgotten about ‘comfort’ as it had been shot down by the scientific community as far back as 2003.  When  I asked several top chair designers at a trade show (2015) all gave  ‘comfort’ as their main objective.    They failed to understand that comfort, free from adverse effects, can only be achieved by an understanding of spinal biomechanics and necessary requirements incorporated into the design. Such a design is, by it’s nature, always comfortable.

This misunderstanding seems to have misled the industry up a wrong path which has resulted in the absence of any chair in the market that is not likely to exacerbate LBP on prolonged use.  Much of the ‘ergonomic’ research on  seating seems, to be based on the ‘comfort’ assumption. For example, “Trial 1. A test chair was created with 35 spring-loaded diodes to measure support in the lower back region by remote control. 200 test persons have adjusted the support in he lower back region again and again until they felt comfortable. The sensors provided the scientists with data which they evaluated using pressure mapping technology. The procedure was repeated several times and the results were clearly confirmed”.   This, based on biomechanically worthless evidence gives no help in assessing what is correct for the underlying spinal constituents.  Even today (2016) a Hermann Miller article writes as it’s 1st principle for design   “1. A chair should be perceived as comfortable before, during, and after sitting upon it. Comfort is as much a matter of the mind as of the body.”.   Perceived by the mind is perhaps OK, but is no substitute for the body (spine) which requires correct biomechanics.

Gorman, who developed the concept of ‘Iliac’ support and has been involved in car seat design, wrote to me   “Comfort tells you nothing” and continues “The car industry has to concentrate on comfort because we spend so much time sitting still in cars. They measure comfort as a lack of localised pressure and have lots of methods to measure it. This used to be large mats of little bubbles which could be individually measured for pressure. Now there are probably much better with mats of pressure sensitive material like large touch screens.  This was always a problem for me when I got my prototypes evaluated by Fiat, Magna, Chrysler, etc. My pelvic support does require force round the iliac crest so even if the seat was subjectively comfortable it would fall down on the pressure measurements”.

Rani Lueder wrote (19/8/12)

“On your comment about comfort, this link to my web pages discusses the origin or this, and the reason that no one really asks about comfort anymore, discomfort is pretty standard. Namely the Corlett and Bishop article (1976) completely turned our head on the issue. They pointed out that not only is comfort nearly impossible to measure in a predictable way, but it is not the opposite of discomfort – and may even be an entirely different dimension” .

Anecdotally, I have seen many chairs pronounced as marvelously comfortable and ergonomically ‘correct’, which have biomechanics faults.  I was asked to see a control room which was responsible for the UK nationwide supply of a major utility. The control room had been optimised for it’s indoor environment so that the air quality, lighting, sound abatement, humidity and colour scheme were marvelous. Everyone was happier, and absenteeism and minor morbidity had decreased. The exception was that backache had remained constant. I found that the workforce, had been allowed to choose the chair. Of course, the most wonderful, expensive, all singing, all dancing chair had been chosen. The staff gave it full marks in the questionnaire. The only trouble was that it gave inadequate support to the lumbar spine.

A chair designed along 2T (3M) principles was judged “This chair is much too comfortable. My work force will go to sleep”. This was the comment of a CEO  who was lying on the prototype P1.  Seat and backrest were of roughly, but correctly, moulded plywood with no padding whatsoever.  This was a common reaction of management.   A 2M (2T, BiModal) or 3M design (TriModal) is based entirely on bio-mechanical research and, pro tem, can be used for comparison to assess the effectiveness of any chair design.

 The 2T is the default  against which the ergonomics of any chair can be assessed.    An essential tool for chair designers. It is optimally comfortable.  2T CONCEPT a full solution→

A converse approach.

The comfort of the 2T concept was constantly remarked regardless of the nature of back & seat components.   This, to some extent,confirmed the working assumption that an optimised configuration would inevitably ensure maximum comfort.  The scientific evidence shows optimised configuration can only occur in a reclined mode.

The ergonomic research approaching from the opposite direction and largely financed by industry, was suspect.   This is changing.  A recent overview editorial by P. Vink in Applied Ergonomics  has evaluated a number of comfort/discomfort models and has proposed a new one.  This draws heavily from the work of Moes, N.C.C.M., 2005 and De Looze,2003.

Although the work of Kee and Lee is described which stresses physical loading and posture holding time,  torque at joints, and compressive force at L5/S1, a number of less bio-mechanic related factors are included.  These include the physical environment + task, psychosocial factors, internal human body effects  and aesthetic design.  Although interesting these are hardly relevant to chair design.                                                 HAS

Next. The 2T chair is intended for office use and office environment in general.  See ☛ 2T in the office→

☛ Exercise & movement→

Next ☛SLEEP →

 

 

EXERCISE & movement

Exercise, spinal movement & change of position are important for a number of reasons including IV disc nutrition, for general health and for the avoidance of LBP.    

Effect of movement on the IV disc

An account of this can be seen at ☛ Disc Nutrition & Spinal 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).

Effect of axial loading  on sitting

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 than was first thought and the general recent ergonomic improvement of office chairs.    Most people prefer sitting, because it is energy efficient with less action by the Erector Spinae & leg muscles than when standing.

The Sit Stand concept

A comeback is occurring as the  importance of keeping staff exercised is recognised and  there are situations where the concept is applicable.   The Sit Stand concept is bio-mechanic superior to the prolonged use of most existing upright chairs and the negative consequences of constrained sitting which has been described by a number of authorities.   On the other hand, although it side-steps the issue of poor office seating it does not address the ergonomic requirements for prolonged work.

 

Screen Shot 2018-06-16 at 13.25.30

A ‘stand’ mode can  be incorporated into the 2T concept with a 3M ‘desk-less’ workstation.  This extra mode results in the  4M workstation, the first change since the inception of the concept in 1998 (and a ‘full’ solution).

Wobbly chairsScreen Shot 2018-09-22 at 14.05.14There is a recognition that prolonged constrained static postures are uncomfortable and deleterious for both spinal and general health.   Recently there has been interest in continuous small amplitude movement for upright chairs, the chair re-aligning with the users centre of gravity,  and termed  ‘Dynamic Seating’.     Exercise is required to maintain this position This provides proprioceptive feedback and frequent small amplitude pressure changes which may be comforting for short periods and helps multifidus muscle action. Rani  Lueder  gives a review account (Lueder R 2002) and the referenced evidence→ is considerable.

Screen Shot 2016-03-14 at 13.35.24

A few chairs are considered in this respect → various chairs. How do they measure up? .

Other ‘movement’  systems

Screen Shot 2015-11-21 at 17.15.57The Dondola hinge system allows a controlled all-round instability and a trial when incorporated in a Wagner chair showed reduction of morbidity when compared to the chair without the system.  However, there have been versions of floating, movable seats over the years with springs, rubber doughnuts, wobbly balls etc.  Not hugely commercially successful, they lacked stability in sitting and so were tiring and uncomfortable particularly for the legs which had to be used to maintain the stability that was not provided by the seat. This may be the same with the Dondola free float but the website is uninformative on the mechanism.   They say   “Nowadays we spend up to 14 hours in a seated position. 50% of all Germans suffer at least once a year from back pain, 25% already suffer chronically. For many this means a permanent Screen Shot 2015-12-12 at 21.10.55psychological strain. The top priority for Wagner is to go against this and increase the performance by caring about the people’s well-being. The most important criteria when buying an office chair, is not if it moves, but how it moves!”

Therapeutic exercise

The effort of balancing to maintain this position exercises the small deep (Multifidus) muscles of the back and helps them to regain their reflex supply following an episode of LBP by what is known as proprioceptive neuromuscular feed back. (☛Muscles→) Spinal instability occurs quickly after any spinal disorder and does not easily recover (Hides Wobble ball1996) so physiotherapist have developed a wobbly ball for therapeutic exercise when the pelvis is in the correct position. Wilke (1999) gives an intradiscal pressure of MPa 0.5 for
sitting on an ergonomic sitting ball with straight back compared to MPa 0.27 when sitting slouched.     Who wants to sit on a wobbly ball in an office?

The 3M (2T) chair

The 2T concept is simple and requires two STABLE positions. (‘stable’ is used in the ergonomic and not the engineering use of the term) and an unstable intermediate transition mode.  With physiological benefits this can be considered as a mode the 2T then becomes a Triple-Mode (3M) concept.  See 2T CONCEPT a full solution→

3M. The 2T inherent exercise system.  The concept has a similar effect in the unstable transitional mode with the uncertain advantage that the lateral component, which may strain the facet joints if used continuously, is avoided. So a patient can exercise discreetly and safely following an episode of backache while using a 2T chair.   It also has the advantage that, although no controls are allowed in this mode, it is under the control of the user by entering one of the 2 stable positions at the end of range.

 3M.  Exercise in the transition mode.

  •  Effort, and abdominal muscle activity is required to bring the chair up from the reclining to the upright sitting mode.  The frequency of this maneuver depends on the number of activities performed in this position   As already described, position changes are important for the nutrition of the intervertebral disc which occurs with spinal movement and in particular by the pumping action of the compression/decompression when changing from a supine to upright posture.
  • A further exercise system emerges when the user moves back a few degrees from the forward upright mode and enters the near upright unstable intermediate mode.   Here small amplitude movement is required providing a choice equivalent to  ‘Dynamic Seating’.
  • Additionally 2T chair has to be pulled or swung towards the work-top or pushed away from it, depending on which mode is suitable for the task in hand.
  • Is all-round wobble would preferable to simple anterior/posterior  instability?

3M. Additional systems

These can include a sprung footrest to provide comforting exercise for the calf muscles. These muscles have an important pumping action to aid venous return to the heart and to prevent venous thrombosis.

 3M. A standing mode is easily included in a 3M workstation and would be an advantage in working with a colleague.  This extra mode results in a workstation.   See ☛ 4M concept.→

Stools

A number of bio-mechanically efficient stools have been produced which usually incorporate a FTS, contouring and sometimes iliac support.

Screen Shot 2015-09-30 at 15.15.20☜ The Pesko ERGO FLEX M 1_1 also incorporates a ‘wobble”.

 Sleep.

A reverse concept!  Short periods of sleep (napping) has benefits resulting in increased productivity   See ☛ SLEEP→

ADJUSTMENTS?

A plethora of adjustments is confusing and can be adverse if adjusted wrongly.  Ideally they should be avoided as far as is possible.

Chair designers place emphasis on variability and adjustability for greater comfort.
“One size does not fit all. The amazing diversity of human form requires a chair that can adapt to different shapes and proportions as well as different heights and weights.”

size1

The variability of the torso shown in these body types is mainly due to the soft tissues. There is surprisingly little variability in the underlying supporting skeleton of the torso.  A greater understanding of spinal anatomy shows that variation occurs at the periphery – the  long (limb) bones and the neck.

Adjustments should be avoided, as far as possible, except for the head and feet and possibly height of seat.  As variation in size of the skeleton of a human torso is not great except for the soft tissues and to the long (limb) bones there is no need for variability to be built into the chair parts that support the torso. With most chairs these are adjusted into the wrong position! This flies in the face of chair designers who are searching for the Holy Grail of infinite adjustability an entirely misplaced endeavour and merely another example of ‘familiarity bias‘.   If a manufacturer prefer a plethora of adjustments, although increasing costs and degrading the green footprint, this does not entirely negate the 2T principles. Although as far as possible, adjustments should be avoided, the footrest position must adjust to leg-length.

Scrapping adjustments

A number of adjustments can be scrapped.  They make the whole system confusing and fiddly, not to mention, expensive.   As shown under the 2T concept the only adjustments required with an anatomically correct design are for the length of the foot-rest, the height of the seat, and vertically and A-P for the head-rest.  Other adjustments should be viewed with scepticism and not as an advantage.   `Scrapping adjustment controls would make any chair more friendly to the user.  Win-Win for everyone including office managers!  Manual adjustments are equivalent to double declutching in motoring.  Days long past!  Misconceived regulations may constrain this concept in some respects but can usually be circumvented.

3D printing in the manufacturing of a 2T chair would allow a ‘ bespoke, tailor-made’ version for individual users and is particularly relevant for those with ‘special needs’.

Variation at the head and neck

In the reclined mode a line of sight to the desk top is required which must accomodate axial variations in neck length and a degree of cervical flexion.  The last can be obtained by reducing the reclination to a more upright configuration which loses some bio-mechanic advantage.  The upper lumbar/thoracic kyphosis can safely be increased as it spans some 14 joints.  The thoracic joints, splinted by the ribs, is regarded as unable to flex but may be able to achieve about 5° overall and more at the upper lumbar joints.  This increase in flexion allows less cervico-thoracic flexion to ensure a horizontal line of sight.

The adjustment for the head-support should be at a lower  thoracic level which would allow flexion to extend over these extra joints.     It has an added advantage by ensuring a correct level for support of the shoulder girdle.

With a FTS in the upright mode the headrest becomes redundant.

 Pelvic support

The initial requirement of the 2T concept is ‘a reclined mode with correct support’. The word ‘correct’ should be emphasised.   There is an unnecessary  and unfortunate tendency, in more expensive chairs, to enable pelvic support to be varied in height.  This is unnecessary as there is little variation in the height of the iliac crest above a flat seat.  Adjustment should be scrapped so that it cannot be adjusted upwards into an adverse height above 20cm when ‘pelvic’ support changes to adverse ‘lumbar’ support.    In my experience adjustments are usually made in the wrong direction.  This was the case with the HM Aeron chair where the pelvic support should be only used at it’s lowest position.   Even this is high for a smallish person.  This height might only slightly reduce the mechanical efficiency for an unusually tall man but will not harm a small woman    Anecdotally, this is certainly my experience when looking at many ‘ergonomic’ chairs.  Invariably the adjustment allows support above 20cm and is commonly so mis-adjusted by the user. In some chairs the depth of pelvic support can be adjusted using an inflatable cushion similar to a sphygmomanometer.  Like any other it can be wrongly adjusted by the user searching for ‘comfort’.    

The design concept appears misconceived.  Only a nudge is required to prevent backward tilting of the pelvis and thereby comfort and, more important, the preservation of lordosis is ensured. Manufacturing costs are reduced. So scrap it!

Screen Shot 2014-02-05 at 11.59.11Screen Shot 2014-02-06 at 14.14.36

 

 

 

 

 

      (by HAS).                                                                (by Wicketts D, after Reynolds et al. 1982153)

For  pelvic (Iliac) support the pressure is directed to the posterior superior iliac spine at 168-146 mm. above the seat (+ 15mm for the soft tissues).  This distance does not vary greatly between individuals, +/- 22 mm.  among the adult population  and for this small amount of variability no adjustment is required.  168 mm. iliac support would be optimal for a large man but adverse for a small woman.  The importance of this measurement for chair design has not been appreciated and further assessments would be welcome.  Three models may be required to cover the top percentile of very large men, the middle percentiles and the bottom percentile for a very small woman.

In the reclined mode of the 2T (3&4M) solution→ , iliac support is only required to prevent the lumbar lordosis from flattening.  In the upright mode it plays no, or little, part  with a FTS but is important and has to be correctly configured if the seat is flat & horizontal or in the ‘ischial off-load’ system.

The height of a chair is important for an upright chair, but less so for a fully reclined chair. Anthropometric tables for popliteal (below knee) height has includes work by Pheasant (1990) and in a more homogenous group of women in the US forces of whom 35% required seats lower than 16 inches (Gordon 1988).  A study (Takeoka 1991 ) of 200 Japanese women concluded that office chairs should adjust down to a height of 141⁄2 inches.   Mandal, for a 671⁄2” (172 cm) girl, found that a tilted seat height of 25” gave a hip angle of 42° and required a table height of 36” (91 cm).

Much of this becomes redundant in the context of the 2 Tilt principles. In the reclined mode the variability in the human torso can be contained in a single construct, provided that there is vertical adjustment for the head and feet. Adjustments may be required for individuals of unusual shape or have deformities, for example permanent adjustment for the width between armrests. Shifting the position of the tilting fulcrum may be required and this adjustment should be effected with an Allan key or spanner by someone who understands anatomy. My observation that most chairs are adjusted into the wrong direction is confirmed by an article in Hermann Miller (research). Three overall sizes can be allowed!   An account of kinematic reclination in the Aeron chair can be seen on the HM website→

Tension control & adjustment

Commonly advertised as a selling point.   I am not sure why.  The  monocoque P3 at MfI, Cambridge had a simple fulcrum tilting method.  I was expecting this to need adjustments but a trial with a large available porter made no difference to the movement.  Would an engineer kindly explain?Photo on 10-08-2012 at 13.16

Uptake? Implications?

  Implications? Familiarity bias.

A chair that is ergonomically superior to any other is likely to have an effect on the market.

  • The ergonomics are the most important attribute for any chair used for prolonged use.
  • The 2T concept has an additional therapeutic advantage with the unstable intermediated (3M) mode.
  • Allows a variety of models, from simple inexpensive to top end, expensive.
  • If a commercial model is shown, by controlled double blind field trials, to be superior to any other chair in the market it is likely to dominate that market.
  • It is easily translated into a workstation.
  • Some chairs are already beginning to appear.   Not fully compliant to the 2T concept, they have failures.   See →WORK-CHAIRS, a new breed with a reclined mode.

Ten years ago, the advantage of the 2T concept was apparent to John Jukes, a pioneer in the optimisation of the office environment  and Prof. Derek Clements-Croom, Director of Research in the School of Construction Management and Engineering at the University of Reading.  Also the reaction of most who had experienced LBP was immediately positive – “Where can I buy this chair” (of course, they couldn’t).   The reaction of chair designers and manufacturers was different.        Blank incomprehension.  Mainly due to ‘Familiarity bias’.

Screen Shot 2015-12-10 at 18.07.31Western people have been indoctrinated that adverse mid upright sitting (See ☛Mandal→) is ergonomically ‘correct’ and have sat in this sort of chair since childhood and so  ‘Familiarity bias’ results. This is a normal reaction of people who have only experienced one way of doing things and results in various levels of denial and incomprehension, when exposed to anything new.  This mind-set can prevent them from seeing the real benefits of a chair that is scientifically shown to be correct but looks different and is actually more comfortable.   It will take time to change this perception and will happen once chairs designed on bio-mechanically correct lines are manufactured and their advantages explained.  Those who are liable to backache will be the first to see the advantages and will create a demand.   The newer generation is more open to fresh ideas and takes quickly to a 2T design.   Insurance is already begining to take an interest (personal communication).

However, as mentioned, perceptions are changing.   At a major international design show in London on 19th Sept. 2013, I found several major Scandinavian and German manufacturers who accepted my views but hesitated to translated them into actual products.  I was even invited to Germany!    This year (2015) several designers said “I have read your views and agree, But…..” .   Which was usually ‘Familiarity Bias’.   Offices of companies like Google, Skype and Facebook, iare like a playground with innovative furniture which would have looked outrageous ten years ago.  The 2T concept that I introduced in 1998 also looked outrageous ten years ago.   It is now begining to look quite ordinary although designers have difficulty in recognising the underlying bio-mechanical essentials.

For example, recliner chairs are only suitable for home use.  A 2T (or 3M) chair is different only because it can be used as a work chair.   Will people buy recliners when a cheaper and better designed dual purpose chair comes on the market?  This may also be particularly relevant to the growing ‘gamer’ market.

To my question “what is the most important factor in chair design?”The answer,  wrongly’ was always :-Comfort. (See Comfort→)

 

This work is not protected and is pro bono publico.    I am available for advice or consultation.   But you will have to be quick!   CONTACT

You are advised to trawl through the whole work to get the full picture.   But for details, see     and check with the menu →

 

Screen Shot 2013-12-31 at 12.36.29
ImplicationsThe physical and emotional stressor effect due to discomfort and LBP is reduced and results in higher productivity.  This offsets the slightly higher cost of a slightly greater footprint which can anyway be completely abolished or reduced by the use of work-stations (See 4M→) or  better office design and layout (see office design).   Anyone who has suffered or is suffering from LBP immediately recognise the significance of a 2T chair and themselves create a demand.     HAS 

Next ☛References→

 

 

 

Office stress & Backache

Psychogenic and backache psychosocial factors.

The new office conditions which give rise to anxiety and fatigue, added to long hours spent in a physiologically unfriendly environment,  leads to high levels of morbidity and breakdown.    The simple explanations for this  state of affairs  is psychological ‘stress’.  An extreme expression of stress is described in America. Dotcom employees with excessive workloads in collapsing companies are found to be sabotaging equipment and systems and attacking fellow staff. This occured when Michael McDemott shot seven people at Edgwater technology.   Security and executive protection companies, such as Pinkertons and Interpahase International have found a recent business increase of 25%.

Psychosocial factors play a part in the aetiology of LBP.  But only a part.

This has received much attention since a Meta-analysis in Occupational Medicine (Waddell 2000).   Ignoring  the Cyriax diagnostic precision, suggests that most backache in the workplace is of psychosocial origin.

Screen Shot 2016-02-05 at 19.22.02

The pendulum of expert opinion is moving away from this extreme view.    Psycho-social factors are hardly a cause of LBP, predicting only 1-5% of new occurrences (  ) but are good predictors of back pain behaviour, as previously recognised by Cyriax.  Depending on the patient’s personality and the surrounding social input and by unsympathetic or inadequate medical, or alternative medical, practice may be important in the management of some cases and can be over emphasised. “Stop complaining and get back to work immediately” is an encouraging message for management in an industrial society which has an increasing problem with LBP and a penchant for litigation.  Psycho-social stress factors, independently of ergonomic stress, are universal and commonly recognised as a cause of office related minor morbidity, absenteeism and reduced productivity.

 Environmental factors,

Air quality, light & noise are stressors and operate on a more basic physio-pathogenic level.   These are probably more aetiologically significant, but less easily  identified by the individual, than psychological stress.   John Jukes, an engineer and productivity consultant  made an unexpected finding when asked to investigate why a Design and Construction Unit (DCU) with a staff of 235 was failing to meet an expected target of 25%  increase of productivity when a CAD system, costing £1.5 million, was installed. They were urged to work harder and productivity actually fell further.  A number of indoor environmental factors were identified.

  • The ergonomics of the chairs and workstations were improved.  Productivity rose.
  • Full spectrum polarised lighting was installed. Productivity rose further.
  • The indoor air  quality (IAQ) was improved with HEPA filters and negative ionisation.
  • The plants recommended by NASA were installed. Productivity rose further.
  • Electrostatic and electromagnetic fields were addressed. Production rose further.
  • The final cost was less per workstation, the 25% target was easily passed and the DCU was able to reduce its workforce by 40%.

Screen Shot 2013-10-23 at 14.10.49 Not only was there an improvement of conditions, likely to be due to environmental deficiencies, improved but also the seemingly psychogenic stress related symptoms. This suggests that if environmental stressors are removed then people can deal more easily with their ongoing psychological stresses.

Indoor environmental stress

 In the home a stress-free environment is at the command of the occupant and is easily achieved. The multi-occupancy workplace, such as an office, is commanded by management and staff, highly paid or not, have to fit in to an often stressful environment which has been determined by cost considerations. The effect this has on reducing productivity is only now slowly coming to be appreciated.

Physiologic Stressors and their remediation.

  • Sub optimal ergonomics.  The subject of this work.
  • Poor lighting.   Indoor lighting is, unlike outdoor lighting, unpolarised.   Lighting by ordinary fluorescent tubes may appear white, but actually only emit light mainly in a narrow band at the yellow end of the spectrum. Only some 8% of the photo-receptors in the retina are stimulated (as compared to 79% in daylight). Added to this, and because of the ‘omni-directional’ nature of the light, some 25% of the light is lost as ‘glare’ – that is, light striking the eye directly and containing no visual information. A 52 cycle ‘flicker’ (in UK) is caused by the conventional ballast of fluorescent tubes. Refresh rate is detected by the eye although not registered by the conscious mind. In addition this rate interacts with that of the VDU screen (at 60-70 cps). This produces an even more deleterious flicker effect.    Halogen lights  generate even more glare.
  •  LightingStress from lighting can be easily and cheaply corrected by the use of full spectrum polarised lighting which aproximates to overcast outdoor conditions, equivalent to the light outdoors on an overcast day (in Washington DC at midday, to be precise)..  As less power is required, running and environmental costs are reduced.
  • Indoor Air Quality (IAQ).  When air conditioning is replaced by HEPA filtration and negative ionisation, reduction in upper respiratory infections and the invigoration of mood has been shown to increase productivity. The system also has the advantage of eliminating modern small airborne particle pollution.   It is equivalent to mountain top air near a waterfall or the air quality that occurs following the electrical discharge of a thunderstorm.  Most offices have the positive ionisation  due to electrical and electromagnetic (EMF) emissions from the multiplicity of machines in the modern office that occurs before a thunderstorm or during prolonged desert winds.
  • Screen Shot 2016-02-05 at 19.09.00Acoustics.  Sound is a far  more common physiological stressor than most people realise. Artificial noises generated by lifts, office equipment and so on tend to cause the body to continuously tense and relax. Poor sound design often means straining to hear your telephone call whilst being over-aware of what’s being said on the other side of the office. A series of hard flat surfaces ( office walls and ceilings ) bounces sound waves into a series of chaotic reflections that are hard to interpret.
    Office equipment generate saw-tooth sounds which in nature are used by animals as aggressive warning signals and square-wave sounds which are used for identification.  A high and prolonged level of noise is rare in nature but poor acoustics in an office leads to raised voices and distraction.    The sounds from office equipment, although discounted by our intelligence, acts as an alarm signal on the primitive part of the brain resulting in a continuous state of unrecognised stress and activation of the hypothalamic-pituitry-adrenal neuro-humeral cascade.
  • Chemical and particulate pollutants are in low concentration in nature and easily dispersed by air currents or denatured by ultra violet light.   The high levels found in industrial society are even higher in an enclosed office space where some are being produced.   A  bewilderingly large array of Volatile Organic Compounds, such as formaldehyde, are given off by new furniture and carpets and are cumulative toxins which can give rise to a number of both mild and serious conditions.

Office environment

The modern air conditioned office is a surprisingly stressful environment. Long hours spent in a physiologically unfriendly environment, leads to high levels of morbidity and breakdown.  Although often not reported, minor morbidity undermines the efficiency and productivity of the individual. Dependent upon the environmental conditions occurring in a particular office this reduction in overall performance ranges from 18% to 52%.

HSE figures reveal that 1 in 11 of the work force suffer occupational health problems, involving 750,000 people, and 1.3 million lost days of production. These figures represent only the tip of an iceberg when considering the vast number of people suffering from minor symptoms which are ignored, being regarded as a part of normal working life. As a large percentage of employees are affected, a lower performance throughout an office can often go undetected if work task efficiency is not measured systematically. There were 164,000 claims for stress related conditions in1999-2000, an increase of a third on the previous year.  270, 000 people daily take a day of work . The cost to the UK is £7 billion a year (Sunday Times 25/3/01).  See ☛Prevalence and economic cost of LBP→

The simple explanations and for this state of affairs is the general assumption that the increase of morbidity is due to emotional stress. Companies have therefore turned to a bewildering variety of stress management strategies. This has given scope to gurus of many hues, starting with stress counseling and release.   There is not yet a general appreciation that environmental factors, air quality, light , noise, are stressors and operate on a more basic physio-pathogenic level and are probably more aetiologically significant, but less easily identified by the individual, than psychological stress. Although psychogenic factors may play a part in the office environment these may not be of prime importance.

 In my experience there have been 2 ‘Paradigm changes’ in this field which are related.
      1. The Cyriax functional examination for soft tissue musculo-skeletal system disorders
      2. John Jukes found that by assessing and reducing indoor physiological stressors that psycho-social stress was reduced and productivity increased by 20-30%.

Cyriax,, in the early 1940s, developed the functional system for the clinical diagnosis of soft tissue musculo-skeletal system disorders at St Thomas’s Hospital, London. This helped us to arrive at an accurate and localised anatomical diagnosis. A number of pseudo- conditions, guesswork and hocus-pocus, that prevailed at that time, therefore became extraneous. At the same time it became possible for this systematic clinical examination to identify a proportion of patients whose symptoms and signs did not correlate and whose signs on examination conflicted and did not add up to anything that suggested an anatomical localisation. These were categorised as ‘psychogenic’ (or p-g, psycho-social) as distinct from a recognisable ‘organic‘ lesion. He found that these patients, even if backache psychosocial factors overlay an ‘organic’ lesion, would fail to respond to treatment. This had to be avoided as treatment tended to continue indefinitely and the symptoms  become perpetuated.      Later the concept of ‘regional pain syndrome’ was developed which might account for some of these conditions on a vague neuro-physiological basis.

 

Screen Shot 2016-05-04 at 11.41.10Environmental Improvements To Health and Productivity

By Stephen Bankler-Jukes, Managing Director, The Optimum Environment Co. Ltd.

Introduction:

Mankind evolved into Homo Sapiens Sapiens  (Modern Man) only some 237,000 years ago; according to recent mytochondrial DNA research conducted by Dr. Chris Stringer of the British Natural History Museum.

However, it’s only been in the last 200 years that any sizeable number of people have spent their working days indoors.  In the course of just the last 100 years, urbanisation has meant that increasing numbers of people have been forced to work indoors by artificial light.

In the last 25 years only have those self-same people been forced to work indoors – and in the presence of artificial flourescent light, air-conditioned heating and cooling, and in the presence of electro-magnetic fields generated by computers, faxes, telephones, printers, and other equipment.   In the same quarter of a century, state-of-the-art chemistry has provided the modern office with a whole range of artificial materials; – glues, finishes, carpeting and fabrics. They all utilise a mix of volatile organic compounds ( such as formaldehyde ) as a curing or hardening agent.  Though mankind does indeed possess a unique ability to mutate to deal with changed circumstances, the range and variety of new assaults on an individual’s physiology are not easily coped with – we simply can’t adapt fast enough. The transition from hunter and farmer, spending most daylight hours outdoors, to sedentary office worker has exacted a toll.   Spiralling rates of “stress-related” illnesses – from short-term problems of head-aches, upper-limb disorders, sore throats etc., – all the way to early morbidity  –  from hyper-tension, heart attacks, addiction, and even suicide… all are by-products of the modern office which have been listed by the (U.S.) Environment Protection Agency and the National Institute of Occupational Safety and Health .

Office Health (& RSI)

This lighthearted effusion, in European Office health & safety (EurOhs), enjoyed a certain success and many comments.  Somewhat dated, many of it’s views were new back in 2003.

Unexpectedly, it is found that this has a certain resonance with the Sit & Stand concept.

Screen Shot 2013-09-28 at 08.04.59Having avoided cholera and other enterics, once we had arrived at our Dickensian workplace we would have found that illumination would have been by full spectrum polarised daylight. This would have given us a 20% stress free advantage over our 21st century contemporaries who are still using conventional narrow spectrum fluorescent tubes with a flicker at 52 cycles/sec emitting a high level.of glare (veiled reflection). As dusk set in we would have returned home to our family or a riotous evening at the local hostelry. If daylight was too short we would have a candle with reflectors. I have one of these and they are perfectly adequate and there is certainly no glare although I would not recommend them for modern use in the ordinary way.

Heating

Our heating would have been by coal fire. These, in case you have forgotten, were cosy and comfortable and keep you active by need for attention. They provide ventilation by drawing in fresh air through cracks around the windows and doors. Further adjustment was by opening the aforesaid. The air movement seemed to address humidity. Of course coal fires raised the outside large size particulate count and S02 which blackened the buildings and had the Darwinian effect of killing a large number of the elderly and infirm when there was an inversion. The London fog was famous and actually romantic and loved by the young. Indoors there was no problem apart from some extra dusting and a raised particle count from the ingress of ambient air. These particles were mainly large and not the more deadly small particles (>0.54 microns) which are present in modern offices. Most air conditioning systems do not filter out these small particles which are derived from outside traffic emissions, power stations, industrial processors, and inside from printer inks and toners and small carbon particles. These last are derived from shed squame (skin) cells which are cooked down by the high tension circuitry in VDUs. Each person sheds about 2 kilos a year amounting to over a ton in an office of 100 people. These particles account for 80% of airborne particles in an office or home and have the ability to absorb and concentrate VOCs, another pollutant which affects modern mankind. The effect of these is carcinogenic and exacerbates Chronic Pulmonary Obstructive Disease (CPOD) particularly asthma. Our forebears would have avoided all of these problems.

Seating

In our early Victorian office, the clerks would probably be sitting on a high stool at a high desk. This is easy to step down from in order to stoke the fire, run errands, find papers and generally keep active. He will not be stuck immobile for long periods in a low chair which has considerable demerits for the spine and venous return. He will be sitting perched forward with his legs tucked under him with feet resting on a crossbar. This position allows the flexion angle of the hips to open up and the pelvis to tilt forward which results in lumbar spinal lordosis (extension). The lordotic position is the natural posture that the spine adopts when standing There are no records suggesting that he was plagued by Low Back Pain as are our modern contemporaries who have to sit for prolonged periods in ergonomically inappropriate chairs. To make matters worse in the modern office the desk may not be adjusted to the height of the chair or the occupant as is required by the recent EU regulations.

RSI

Our clerk could suffer from RSI – or more terminologically exact, Work Related Upper Limb Disorder (WRULD). It would have been called ‘writers cramp’ having previously been described in 1713 as “scriveners palsy’ by Bernadino Ramazzini who is credited as the founder of occupational medicine. In 1892 the neurologist Sir William Gowers described the condition as an ‘occupational neurosis’ and Professor David Ferguson of the University of Sidney went further to describe the Australian epidemic of 1984/85 as a “complex psychosocial phenomenon with elements of mass hysteria, which were superimposed on a basis of widespread discomfort, fatigue and morbidity”. This view was reinforced by Barton et al in a report on behalf of the British Orthopaedic Association submitted to the Industrial Injuries Advisory Council in 1990. The current critical view has changed in that certain specific anatomically localised lesion such as tenosynovitis of various tendons around the wrist, carpal tunnel syndrome and epicondylitis, of either the ‘tennis’ or ‘golfers’ variety, can be work related as well as the less certain ‘regional pain syndromes’ which are of complex neuropathic origin.

This latter group is unimaginatively described as ‘WRULD Type 2′ and is recognised as having a psycho social dimension and related to work stress. To this we will return.

Indoor office environment

Empirically it has been found that optimum remediation results in the indoor environment being made to approximate to an equable outdoor temperate environment. Lighting must either be by suitably adjusted daylight or by full spectrum polarised light which is nearly equivalent to daylight. Savannah and mountain top air is relatively free of pathogenic microbe, and certainly VOCs. In an office environment it is found that installation of HEPA filtration and negative ionisation results in reduced sickness and an increased sense of well being which is translated into increased productivity. This system has the added advantage of eliminating the small airborne particles. As mentioned, these are a product of industrial civilisation and they can be borne over large distances, including national boundaries, remediation cannot be effected by relocating to a ‘green field’ site. Another physiological stressor are the sounds produced by modern office machinery. These are of a type that are interpreted by our primitive brain as alarm signals and so, although discounted by our modern brain, act as stressors.

The aforementioned can be easily remediated as indicated. The cost is not great and will be recouped in 1-2 years by increased levels of productivity. An unexpected finding in the optimised office is that measurable stress levels are reduced. It would seem that removing the physiological stressors enables the individual to cope with the psychological stress that effects most people under modern working conditions.

MSDs

The musclo-skeletal disorders which are so common in recent times are partly due to lack of exercise as well as to the production of artefacts to enable work to be done in an unphysiological sitting posture. This simply did not pertain to our Cro-Magnon ancestors. As an Orthopaedic Physician a large part of my work consists of dealing with spinal disorders and I would endorse Mandals conclusion that “without the slightest regard for man’s actual anatomy, a new human form has been contrived to fit the available furniture.” To which it could be added that chair designers and manufacturers continue, with great ingenuity, to make chairs to this design. The new design of chair incorporating iliac (or pelvic) support rather than ‘lumbar’ support is an advance, but we need to go further, with a fresh rethink, if our occupation continues to require prolonged sitting. Desking has to be considered in relation to the person sitting in the chair and the height of the chair adjustment. Variable desk height adjustment is therefore a minimal requirement. A new generation of desks is slowly coming on to the market which take into account the need for wrist support as well as easily accessed communications and even a localised optimum environment!

Ergonomics

As for RSI (OK, lets use the outdated terminology; everyone else does), a two prong approach is necessary. Firstly the ergonomic factors have to be corrected such as workstation layout, well designed tools, positioning and wrist supports as well as breaks for alternative activities (a computer programme called ‘Workpace’ is useful here). Secondly, as mentioned, psychosocial factors are paramount in the WRULD Type 2 condition. Interestingly, it has been found that in an environmentally optimised office not only are the obvious morbidity rates reduced but that also stress related symptoms largely disappear. This suggests that as the physiological stress is reduced the worker can manage their own psychological stresses. This is very relevant to the psychosocial aetiology of the WRULD Type 2. Finally it must be emphasised that RSI is a potentially serious condition in that it can permanently curtail the continuance of a career. The problem must be recognised early and steps taken to remedy any ergonomic and environmental cause. To be successful Type I treatment must also be undertaken early by someone trained in the treatment of soft tissue injuries. At a later stage, Type 2 treatment is often surprisingly complex and requires a ‘pain clinic’ approach.

Screen Shot 2013-09-28 at 08.18.28To conclude, a healthy office environment is one that approximates to the equitable outdoor environment for which Homo Sapiens was developed by natural selection. The further we depart from this the greater the morbidity levels rise.

Obvious, really.

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Points for this article were taken from :-

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