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Risk Factors and Sources of Injury > Incorrect Work Surface Height          
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Ergonomic Workstation Graphic

Incorrect Work Surface Height

What is the Correct Height to Position the Work Surface?

The primary work surface (where the keyboard and mouse are located) should be located just above the top of the thighs, with a neutral or slightly negative inclination. This should result in the forearms (and hands) being parallel to the ground or slightly negative while working (as shown in the images on this page). The upper arms should be near vertical, elbows below the shoulders, and at rest at the sides (the anatomically neutral position). The keyboard and mouse must be at the same height on the same work surface as there is only one optimal height when working.

Why is Improper Work Surface Height a Risk Factor?

...If the Worksurface is Too High
The user will be forced to raise their arms and/or shoulders to gain access. This puts a static load on the muscles and ligaments 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 downward at the wrist, or Palmar Flexion) 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 their upper body forward or stretch their arms away from the body, which can cause back strain and stress to the arms while attempting to perform tasks. In addition, the wrists will be forced to be in a position of Wrist Extension (i.e. be bent upward at the wrist) 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?

Ergonomic Workstation Graphic

There is a very low level of tolerance in both the wrist and shoulders for most individuals; taller individuals usually have increased tolerance than shorter individuals due to their longer average arm length. As such, anything more than 1" higher or 2" lower than the optimal height at a sitting workstation would represent a risk factor. For standing workstations, there is typically slightly more tolerance to a lower height, so anything more than 1" higher or 3" lower than the optimal height at a standing workstation would represent a risk factor. 

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

Symptoms that may indicate that the worksurface is at an incorrect height are strain in the arms, shoulders, wrists and back. There is also the possibility of tension and pain developing in the neck as the body attempts to compensate.

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 6'0". Articulating Keyboard Arms will allow a keyboard tray to be adjusted below the worksurface (and sometimes above) to the optimal height where the elbow is higher than the wrist. Another alternative is to replace the desk with an Adjustable Height or Sit Stand Workstations which will adjust not only a small keyboard tray but also elevate 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?

Adjusting the Chair
By raising the height of the seat, it may be possible to achieve the proper relative arm height. Note: This will usually also require the addition of a Foot Rest to prevent dangling feet.

Adjusting the Worksurface
If a worksurface needs to be adjusted upwards, there are Desk Risers available which can elevate the worksurface.

Last edited July 18th, 2018

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