asd - when sitting correctly matters

8/11/2019 ASD - When Sitting Correctly Matters

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How posture affects disc pressure

w h e n s i t t i n g c o r r e c t l y m a t t e r s

Advance Seating designs

Unit H, Field Way, Metropolitan Park, Greenford, Middlesex UB6 8UN UKTelephone: +44 (0)20-8578 4308 Fax: +44 (0)20-8578 4352

E-mail: [email protected] Web site: www.asd.co.uk 41103

100% +105% +115% +140% +190%

Back angle

110 100 90 80

Disc pressure

Adopt a new angle while workingUsing a keyboard or writing means you have to lean

forwards to work. This encourages a slouched un-healthy posture (80 angle).

However, you can achieve a 100 or 110 angle andrestore the natural balance to your spine by setting thechair seat level or tilting it slightly forwards(1).

The dangers of sitting

Changing from a standing to a sitting position makes

the top of the pelvis rotate backwards. This flattens thenatural lumbar curve of the spine, causing an increaseduneven pressure on the intervertebral discs.

On leaning forwards (80 angle) the spine describes aC shape, further increasing lumbar disc pressure(+190%) and extra strain is placed on the back muscles.

How posture controls disc pressure

The secret of sitting to reduce disc pressure is toencourage the spine to lengthen into its neutralbalanced position, as when standing.

By sitting upright and leaning slightly backwards (100angle) the top of the pelvis rotates forwards allowingthe spine to hold its natural S shape. There is a betterbalance in the spinal column, with the head centrallypositioned over the spinal column, and less activity isrequired from the supporting musculature. Weight ismore evenly distributed across the intervertebral discs.

The effect of four postureson the intervertebral discpressure as measuredbetween the 3rd & 4thlumbar vertebrae. Thepressure when standingis taken as 100%.According toNachemson andElfstrom.

(1) The use of a forward tilting seat is not advisable for certainmedical conditions, if there is any pain do not persist, use the seat ina level position or where comfortable. Initially vary posture regularlyto allow muscle groups to adjust to the new position.

100-105 100-110Seat level

Seat

angle

Seat tilted forwards

By occasionally adjusting the seat angle while you workyou will derive the most benefit, the body is designedfor movement. Change your posture to suit the task. Tostabilise the lower part of the spine, which in turncontrols balance in the upper spine, sit well back inyour chair to maintain contact with the backrest.


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the ideal posture


Unit H, Field Way, Metropolitan Park, Greenford, Middlesex UB6 8UN UK

Telephone: +44 (0)20-8578 4308 Fax: +44 (0)20-8578 4352

E-mail: [email protected] Web site: www.asd.co.uk


when using a computer when writing

PostureLengthen spine into its natural balanced position,keeping head held over the shoulders and in line withthe buttocks.

ChairTilt seat forwards or level according to comfort ormedical requirement.(1)Adjust seat height so hip jointis slightly higher than knee joint.

Desk heightMiddle row of the keyboard should be level with theelbow, (forearms parallel to the floor).If the desk is too low raise with desk feet, if too highuse a foot stand and raise seat height.Place mouse in easy reach zone by keyboard.

ScreenShould be at arms length and on eye level in front ofthe user (visual angle 0-21).Position at 90 to any light source avoiding glare orreflections. Use copy holder so input data is withinfield of view.

TelephoneIf used for more than 40% of the working day considera headset to free hands for more efficient working.

SpaceCreate sufficient room to work especially ifmultitasking. Place equipment on stands or arms ifnecessary.

MovementPrevent static loading. Rock, change position to reducefatigue. Place one foot in front of the other, alternateposition during the day. Take breaks and vary tasks.

PostureLengthen spine into its natural balanced position,keeping head held over the shoulders and in line withthe buttocks.

ChairTilt seat forwards or level according to comfort ormedical requirement (1). Adjust seat height so hip jointis slightly higher than knee joint.

Desk heightElbow should be just below the desk top. If the desk istoo low raise with desk feet, if too high use a footstand and raise seat height.

Writing slopeRaise work using a slope. This reduces viewing distance,lessens eye strain and limits the body leaning forwards.Hold the head upright to maintain a balanced spinalposture.If taking notes from a book keep it within the field ofview using a book attachment above the slope.

TelephoneIf used for more than 40% of the working day considera headset to free hands for more efficient working.

SpaceCreate sufficient room to work especially ifmultitasking. Place equipment on stands or arms ifnecessary.

MovementPrevent static loading. Rock, change position to reducefatigue. Place one foot in front of the other, alternateposition during the day. Take breaks and vary tasks.

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The secret of sitting correctly is to encourage the spine to lengthen into

its neutral balanced position.

The pelvis should tilt forwards allowing the spine to hold its natural S

shape.

This means weight is evenly distributed across the intervertebral discsand there is a better balance in the supporting musculature.

how to sit correctly


unhealthy

PelvisPelvis crest forced to lean back.

Spinal columnStrained spinal column, withcompression of the lumbar discs.

BreathingRestricted, only using upper part ofchest.

Lower abdomenCompressed. Poor digestion.

CirculationRestricted.

MovementLimited.

MusclesElongated in back, slack in abdomen.Imbalance can weaken lower back

PelvisPelvis crest rotated forwards (1)

Spinal columnExtended spinal column, with evenweight distribution on lumbar discsand balanced musculature.

BreathingUnrestricted, using diaphragm andupper part of chest.

Lower abdomenNot compressed. Improved digestion.

CirculationUnrestricted.

MovementGreater freedom of movement.

MusclesLess strain on back, abdomen toned.Balance maintained, lower back keptstrong.

healthy

Kyphotic spine

angle of pelvis crestmakes spine go into aC shape

Lordotic spine

angle of pelvis crestmakes spine go intoan S shape



Telephone: +44 (0)20-8578 4308 Fax: +44 (0)20-8578 4352

E-mail: [email protected] Web site: www.asd.co.uk

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Sitting

Arm Position very importantForearm should be horizontal to the floor with elbow,wrist and fingertips in a straight line to the top of themouse.Keep the shoulders relaxed with elbows tucked incomfortably by ones side with a 90 angle betweenlower/upper arm.

Avoid constant clicking with the arm straight andfingers tense.

The chairUse a fully adjustable chair with back/seat depthsuited for your stature/size.The seat should be level or slightly tilted forwards.(1)

Adjust seat height so the hip joint is slightly higherthan the knee joint.Sit well back into the chair to support the spine/pelvis.Rock, change posture, to increase blood flow andreduce fatigue.

Desk heightIf the desk is too low use Desk Feet to raise it. If yourdesk is too high use a Foot Stand and raise the seatheight.

SpaceArrange desk layout to give ease of movement.Use a mouse plate attached to the desk/chair if spaceis limited in the easy reach zone.

using a mouse


90

The key to healthy mousing is that the workstation must suit

the user with the height and positioning of the equipment

being correct for their stature. The mouse must be within easy

reach, with sufficient space for it to be used in a relaxed,comfortable manner.

Mousing

Mouse sizeCheck that it fits comfortably into the hand.

Mouse positionKeep it close to one side of the keyboard, within theEasy Reach zone and use a mouse mat.Position to avoid cable drag and leave space for

adequate movement. (i.e. mind the coffee cup!)

TipsAvoid quick repetitive movements.Watch the wrist angle:

Use function commands on the keyboard, a wheel onthe mouse or programmable buttons if possible.Keep mouse pad clean so the contact ball and wheelsmove freely.Replace a mouse immediately if buttons become faulty.Break up mousing activity with other tasks.



Telephone: +44 (0)20-8578 4308 Fax: +44 (0)20-8578 4352E-mail: [email protected] Web site: www.asd.co.uk


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asd - when sitting correctly matters

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