Wednesday, April 13, 2011

Computer Monitor Height

If you were to get into your friend’s car to take a quick ride down to the store what is the first thing you would do before departing? Most of us would adjust the driver’s seat to compensate for a difference in size or stature to provide us with a comfortable short commute. Interestingly, on the contrary when a worker inherits a new workstation many times I find that the worker will diligently sit down and begin productive work without making adjustments to their workspace.

Monitor position is often one area that gets overlooked. Ergonomic monitor position is considered to be centered in front of the worker, about 20-25” (arms length) away from the worker with the top of the monitor screen at eye level.

The monitor should be positioned directly in front of the worker to allow for a neutral head position. If the monitor is positioned to the left or the right it tightens all the muscles and compacts the joints on that side of the neck, leading to muscle soreness. I equate this to falling asleep on the couch watching football for an hour or two with your neck in an awkward position. You would waken to the realization of a sore neck. The same is true from rotating to the right or left to see you monitor but that is for 8 hours a day, 5 days a week.

To prevent neck and upper back fatigue it is vital that the monitor is positioned close enough to the worker to prevent them from straining their eyes. For most of us this is about an arms length away. In the 1990s and early 2000s most of our monitor were encased in a box that was anywhere from 12”-18” deep, therefore the constraints in the depth of our desk top often kept the screen of our monitor at the proper distance. With the more modern flat screens we now have a monitor that has only 2-4” of depth. As a result, we have the temptation to put the monitor toward the back of our desk space to open up much needed real-estate on the front of our desk to place our coffee, pens and work papers. The problem with this is that this puts our monitors greater than an arms reach away causing eye fatigue. Because of this fatigue, we tend to extend our necks forward and slouch at our upper back to make the monitor an arms length away from our eyes. The human head weighs about 10 pounds. The strain of this position is similar to holding a bowling ball at arms length. The leverage caused from long lever arm to the weight would strain the muscles in our arms and shoulders. The same is true with our heads. Forward head posture gives our head leverage over our body putting additional strain on our neck muscles causing them to shorten and fatigue.

Monitor height is also crucial for good neck and upper back positioning. A monitor that is positioned above eye level forces the muscles that rotate your eyes upward to fatigue. As a result your eyes will return to a neutral position (looking straight ahead). To continue to see the monitor you will extend your neck compacting the joints and putting the neck extensors in a static contraction causing fatigue and eventual discomfort. A monitor that is too low will cause workers to look downward and often slouch at their shoulders, causing fatigue and discomfort. This rule gets thrown out for those of you who use bifocal or progressive glasses. With these types of glasses the line that allows you to focus is often in the lower portion of the glasses. Therefore, the position of your monitor should be below eye level, at a height where your neck is in a neutral position.

The key to ergonomics is to make the workspace fit the worker rather than the worker fit the workspace. Remember that our bodies will tend to deform into the position that we put them in most. Work posture outside of a neutral position will often cause a variety of aches and pains and in some cases injuries. For monitor positioning equipment has some great equipment.