Category Archives: HOME. Backache and chairs

Back pain and chairs. The biomechanical (ergonomic) factors resulting in backache (LBP) and the requirements for remediation.

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The SCIENCE

It is hoped that this may provide a resource for designers and users of work chairs.  There is a large body of research and background, on spinal bio-mechanics, which you may wish to explore.

OBJECT. To identify and address  the adverse bio-mechanic (ergonomic)  factors that  potentially were liable to result in spinal component break down which can account for Low Back Pain (LBP, backache and more serious disorders, IDD, CTD.)  in relation to the seated posture, 

METHOD.   Existing work on spinal pathology and biomechanics related to upright seated posture  was  explored.

CONCLUSION.  The evidence identified adverse effects which occur with conventional prolonged mid-upright sitting that required remediation.   It was found that a reclined mode is the only position that avoids all the adverse effects of prolonged upright sitting.  This conclusion became validated  by independent work using pMRI scanning (Smith 2007)  

 

The 2 TILT  chair CONCEPT.

The big story here, however, is that it was found that a reclined mode is the only position that avoids all the adverse effects of prolonged upright sitting.    For a reclined office work-chair to be practical a number of requirements are essential.  These have been covered in the 2Tilt concept which was tested for practicality in the Cambridge MfI department.

Screen Shot 2016-03-18 at 19.28.20The 2T concept addresses all the ergonomic factors  that  ensure a sitting position that is the least likely to perpetuate, or result in, backache and other spinal conditions. It also includes the necessary requirements to make this a user-friendly practical work-chair.  Comfort → is also thereby maximised.
The 2T concept is fully described by following  ☛A Full solution→
Briefly it involves :-

1 A Reclined mode

  • sitting safely reclined modeA fully body support reclined mode, configured to the correct spinal  shape. is optimal for prolonged work.  ☛The 2T reclined mode→
  • The reclined mode requires head support that allows for a forward vision field.
  • Variability at head and feet only.  Avoided elsewhere. Adjustments→.

2.sitting safely upright mode  An  Upright Mode (eg. forward tilted seat,) is subsidiary but  required for certain short activities and quitting the chair and is the default mode when the chair is unoccupied.  ☛2T Upright modes→

3. Screen Shot 2015-10-07 at 13.43.22The mid ranges should be unstable and easily negotiated    ☛Unstable intermediate mode →.  This is to avoid  the conventional adverse mid-upright sitting posture.  It can be used for short periods as a form of exercise ( ☛ dynamic seating→), particularly for rehabilitation  following an acute attack of Backache.

4. This leads on to the QuadriModal 4M work-station→.

The 2T concept is fully described by following  ☛A Full solution→

Navigation.

The menu on the right→ indicates the layout and lists more posts than the main top menu.     Next  ☛  How to use this work →

Managing the Ergonomics of Office Seating

 by John Jukes                  The Source Publishing Company Limited 

Ergonomics expert John Jukes asks is the Sit/Stand desk the answer to aches and pains in the office?

Research done by Dr Henry Sanford, Orthopaedic Consultant at the Cromwell Hospital, adds another dimension to the problem of ergonomic comfort in the office. Sitting in a semi reclined position at 45 degrees reduces the gravitational loading on the spine by 50%. This is similar to the astronaut position, which permits working under heavy G forces. A suitable headrest and positioning of keyboard and VDU screen makes this a perfectly practical working position without inducing sleep. Many programmers, CAD users, control room engineers and tall people are seen to adopt this position using an ordinary chair when  working for long periods – perching the tail on the front edge of the chair with their shoulder on the back and the legs out straight.

Sit/stand desks and pelvic support semi recline seating  in the UK have yet to become part of the normal office landscape. When they do there will be several million office workers that will be grateful to be free from daily debilitating pain.

He wrote

HAS & M19.08.43Dr Henry Sanford MA. MB. B Chir. (Cantab) D  Phys Med. (Lond) is a well known Consultant Orthopaedic Physician in London and Associate Consultant to the Department of Rheumatology, St Thomas’s Hospital, SE1.  Earlier he worked at St Thomas’s with Dr J H Cyriax who is regarded as the ‘Father’ of  Orthopaedic (or Musculo-skeletal) Medicine after following 2 years in the army finishing as a Captain in the RAMC.

He was a founder member of the Society of Orthopaedic Medicine (SOM), the British Society of Musculo-skeletal Medicine (BIMM) and was Chairman of the Cyriax Organisation..  He has run courses and lectured internationally                                                              John Jukes – 30/07/2001     Site Navigation→

Copyright2016

NAVIGATION. To use this work

The Layout Arrangement of this work.

For some readers this study was too large and diffuse.   It is now divided into subdivisions.

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Screen Shot 2016-03-18 at 08.41.28To remediation2T direction

 

 

This is indicated in the top menu↑.   All post are shown in the menu on the right→ .       Specialists will prefer to jump directly to their page of interest using the Right menu→.

For an overview of contents…..

Screen Shot 2016-05-16 at 18.50.05Designers are the intended readers and,  apart from some duplication, are advised to read the whole work.  This includes a large body of research and background, on spinal bio-mechanics.

Screen Shot 2016-05-17 at 15.59.14 Manufacturers can be reassured that feasibility indicates that existing components can be used , Screen Shot 2017-05-23 at 07.52.02avoiding the expense of retooling, while preserving their brand image.   Prospective manufacturers can be helped to leap ahead of the field,  ☛  →

New ideas can create both threats and opportunities , once both familiarity  and normalcy biases are overcome.  Creative disruption works.

Topics and some relevant subjects

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to architects

For New offices ‘Coolness’ is the word to  excite media interest for both the company and the Architect/Designer.   Most firms aspire to project this cutting edge image.    A 2T chair, or the derived 4M workstation, answers this exactly and in addition reduces LBP and increases productivity by lessened morbidity and stress.  Also see  ☛  PRODUCTIVITY AND WORKPLACE STRESSORS→(Article published in EurOhs, European Occupational Health and Safety Journal, Dec 2002.by Dr HA Sanford)

To office managersAllows an alternative view to the usual hype, often laughably misguided, from manufacturers,

 

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For GENERAL USERS→

Also of LIKELY INTEREST to a general reader

To remediationBackache & chairs.   A number of systems are described.  Spinal bio-mechanics dictates that prolonged sitting should be performed in a reclined position with frequent change of posture.  For a full remediation  a number of requirements are essential.   To be effective these are detailed in the 2 Tilt (2T) concept.

Requirements for optimising the bio-mechanics of prolonged sittingScreen Shot 2016-03-17 at 13.34.53

Partial remediations.

Partial solutionsSystems in use at present,    See ☛ Remediation→

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. Shown here is the Okamura ‘Atlas’ chair.  ☛ Atlas→

Screen Shot 2013-09-29 at 14.29.22Other, commonly used partial solutions include ☛ Pelvic support→,

 ☛forward tilted seat→, & Ischial off-load →

& ☛Sit/Stand→.

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A full remediation, the 2Tilt Concept, is suggested.  See ☛ 2T concept→

Screen Shot 2016-03-12 at 16.17.49Combining these requirements can be difficult to achieve but is possible in a suitably supported reclined mode at 40-45° which conforms to spinal morphology (configuration). This alone is impractical as a work position unless a number of secondary requirements are incorporated to make this simple concept suitable and practical for a work chair.

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  1. screen-shot-2016-09-21-at-10-13-41A reclined mode for prolonged work    ☛2T reclined mode→
  2. An upright mode required for certain jobs.    ☛2T Upright mode→
  3. An unstable intermediate mode to enable a quick, easy transition between the 2T modes.    ☛2T transition mode→    ☛ dynamic seating→  With the recognition that the transition movement has physiological advantages, this has been upgraded to a ‘mode’.  The 2T now becomes a triple-mode (3M) concept.
  • A sit/stand facility can be incorporated to become a 4M version.    ☛Sit/Stand→

 

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‘Sitting disease’

Compared to people who sit the least, those who spend most time in a chair have a 112 % higher risk of developing diabetes, a 147% higher risk of suffering “cardiovascular events” such as strokes and a 49%t increased risk of death from any cause.  (http://www.telegraph.co.uk/wellbeing/fitness/sitting-disease-is-killing-us-and-exercise-doesnt-help/)   Alarming but not entirely an effect of the bio-mechanics and not examined here.  However some posts are relevant.

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 ☛  →

Managing the Ergonomics

Managing the Ergonomics of Office Seating

 by John Jukes                       The Source Publishing Company Limited 

Ergonomics expert John Jukes asks is the Sit/Stand desk the answer to aches and pains in the office?

Research done by Dr Henry Sanford see, Orthopaedic Consultant at the Cromwell Hospital adds another dimension to the problem of ergonomic comfort in the office. Sitting in a semi reclined position at 45 degrees reduces the gravitational loading on the spine by 50%. This is similar to the astronaut position, which permits working under heavy G forces. A suitable headrest and positioning of keyboard and VDU screen makes this a perfectly practical working position without inducing sleep. Many programmers, CAD users, control room engineers and tall people are seen to adopt this position using an ordinary chair when  working for long periods – perching the tail on the front edge of the chair with their shoulder on the back and the legs out straight.

Sit/stand desks and pelvic support semi recline seating  in the UK have yet to become part of the normal office landscape. When they do there will be several million office workers that will be grateful to be free from daily debilitating pain.

 

He wrote

Dr Henry Sanford MA. MB. B Chir. (Cantab) D  Phys Med. (Lond) is a well known Consultant Orthopaedic Physician in London and Associate Consultant to the Department of Rheumatology, St Thomas’s Hospital, SE1.  Earlier he worked at St Thomas’s with Dr J H Cyriax who is regarded as the ‘Father’ of  Orthopaedic (or Musculo-skeletal) Medicine after following 2 years in the army finishing as a Captain in the RAMC.

He was a founder member of the Society of Orthopaedic Medicine (SOM), the British Society of Musculo-skeletal Medicine (BIMM) and was Chairman of the Cyriax Organisation..  He has run courses and lectured internationally                                                              John Jukes – 30/07/2001

 

HAS19.07.34HAS & M19.08.43                  

 

 

 

 

HAS in BAOR,1954

and with daughter, Marietta, in Cambridge, 2005.

Prevalence and economic cost of LBP.

 The increasing backache prevalence seems to be a genuine phenomenon of the 20th/21st centuries in Western societies at the same time as the increase in sedentary occupations and lack of exercise ..  The scale of mechanical  Low Back Pain (LBP) problems is confirmed by many studies from many countries.

There has been a slight drop in prevalence in the last few years.  Perhaps it is presumptuous to suggest that this may be due to improved seating following my views put forward  in 1998 although a full 2T chair is not yet in the market.

LBP is the most common health problem for British workers. The Clinical Standards Advisory Group (Waddell), in 1994, in a study of the  backache prevalence and it’s cost  estimated that, since 1978 the  annual loss of working days due to low back pain had increased 200% to 150 million days.    A study in Manchester (Croft 1998) showed that 50% of women aged 45-50 claimed to have suffered from backache in the previous  month.  A prospective UK trial (Croft 1999) showed a 36% increase in prevalence of backache and incidence rate in 1 year.    Since then there has been a slight drop possibly due to better designed chairs, many of which are slowly approaching my views.

Back pain is also one of the most costly conditions for which an economic analysis has been carried out in the UK and this is in line with findings in other countries. It is estimated that the direct health care cost of back pain in 1998 to be £1632 million.  Approximately 35% of this cost is most likely paid for directly by patients. With respect to the distribution of cost across different providers, 37% relates to care provided by physiotherapists and allied specialists, 31% is incurred in the hospital sector, 14% relates to primary care, 7% to medication, 6% to community care and 5% to radiology and imaging used for investigation purposes. However, the direct cost of back pain is insignificant compared to the cost of informal care and the production losses related to it, which total £10668 million.  (Maniadakis N, Gray A. 2001)   (Maniadakis N, Gray A. The economic burden of back pain in the UK. Pain. 2000 Jan;84(1):95-103.)

The Centre for Health Economics (CHE) showed a cost to the UK NHS of £265.3 billion – £382.7 billion in 1992-93.  https://www.york.ac.uk/che/pdf/DP129.pdf

The Work Foundation estimates that employees suffering from bone and joint pain cost the EU’s economies 240bn euros (£200bn) each year.  “Sitting is the new smoking,” explains Prof Steve Bevan, director of the Centre for Workforce Effectiveness at the Work Foundation.  “The more sedentary you are the worse it is for your health.”   The Lancet, published a study in 2012, which found that musculoskeletal conditions were the second greatest cause of disability in the world, affecting over 1.7 billion people worldwide.  “I describe suffering from musculoskeletal disorders as being like a Ferrari without wheels,” says Prof Woolf, who is also the chair of Bone and Joint Decade. “If you don’t have mobility and dexterity, it doesn’t matter how healthy the rest of your body is.”

In the United States About 100 million workdays are lost annually  (Johanning 2000).  Insurance figures show that 82% of US office workers complain of LBP (personal communication 2012 HAS),   Lower back pain’s economic impact is shown to be the number one reason for individuals under the age of 45 to limit their activity, second highest complaint seen in physician’s offices, fifth most common requirement for hospitalization, and the third leading cause for surgery.  (Health and Safety Executive‘s Better Backs campaign.https://en.wikipedia.org/wiki/Health_and_Safety_Executive).

The actual increase of mechanical spinal pathology and backache prevalence seems to be a genuine phenomenon of the 20th century and is rising exponentially (Hemingway 1997) with the increase in sedentary occupations.”Mankind has progressed from Homo sapiens to ‘Homo sedans” (Mandal).

(Prevalence = the number of existing cases overall.   Incidence = the number of new cases in a given time.)

Next ☛BACKACHE? For users and patients (only)

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