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Risk Factors and Sources of Injury > Improper Work Surface Height          
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Ergonomic Workstation GraphicImproper Work Surface Height

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What is an Improper Work Surface Height?

The primary work surface (where the keyboard and mouse are located) should be just above the legs of the user with a neutral or slightly negative inclination. This should result in forearms (and hands) which are parallel to the ground or slightly negative while working. It is very important to have both keyboard and mouse on the same work surface and at the same height as there is only one comfortable height when seated in an relaxed posture.

Why is Improper Work Surface Height a Risk Factor?

If the worksurface is too high, the user is forced to raise their arms and/or shoulders. This puts a 'static load' on the muscles since they are required to be constantly engaged to maintain position.  In addition, the underside of the forearm or wrist will experience a compression point wherever they press against the edge of the worksurface.  Finally, the wrist may have to flex (i.e. bend forward) to perform required tasks (keyboarding / mousing) placing additional stress on the forearm and wrist.

If the worksurface is too low, the user is forced to lean forward, which can cause back strain and stress to the arms in attempting to perform tasks.  In addition, the wrists will be forced to be in a position of Wrist Extension (i.e. be bent upward) in order to perform keyboarding and mousing tasks.

How Specific a Height does a Work Surface have to be to avoid it being a Risk Factor?

There is a very low level of tolerance in the wrist for most individuals and anything more than 1" higher or 2" lower than the ideal would represent a risk factor.  This applies to both sitting and standing workstations. 

What are the Symptoms of a Work Surface which is 'Too High' or 'Too Low'?

Symptoms that indicate that the worksurface is at an improper height are strain in the arms, shoulders, wrists and back.

How can the Choice of Workstation Help to Reduce Improper Work Surface Height?

Most standard desks have a height of 29" which is too high for most individuals under 5'11" in height.  Articulating Keyboard Arms will allow a keyboard tray to be adjusted downwards to the desired height to allow the elbow to be higher than the wrist when the upper arms are at rest at the sides.  Another alternative is to replace the desk with an Adjustable or Sit Stand Workstation which will adjust not only a small keyboard tray but also adjust an entire desktop to the ideal height, for sitting, standing, and all positions in between.

What Other Strategies can be used to Address Work Surface Height?

There are various other strategies to address this issue.  By raising the height of the chair seat, the proper relative height at the arm can be achieved but there may be a requirement to add a Foot Rest to prevent dangling of the feet.  If a worksurface needs to be adjusted upwards, there are risers available which will raise the worksurface by various means.


Last edited December 16th, 2013

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