Office Workstation Ergonomics and Positioning
How to adjust your workspace to avoid injuries.
Being a Chairborne Ranger isn’t very glamorous. Unfortunately, it’s also bad for our health. Studies have shown that extended seated work increases the risk of cardiovascular diseases, diabetes, and a number of other chronic ailments. Seated work is terrible for our spines and a common source of work-related musculoskeletal disorders (MSDs) that costs employers a fortune. Being in very good physical condition can reduce the likelihood of a person developing (MSDs), but this is by no means an absolute; in the U.S. Marine Corps, one of the greatest sources of loss is lower back ailments caused by seated work.
Can You Adjust?
We can’t eliminate all loss caused by seated office life, but we can reduce it by incorporating more ergonomically friendly workstation components. The more adjustable the components are, the better! A worker can orient the wrists to be as straight as possible when typing and using the mouse by having the elbows roughly level with the desk surface, which may involve lowering the height of the chair. However, if this results in the chair being so low that the worker is looking upward at a non-adjustable monitor and experiencing eye and neck discomfort, then the choice will have to be made between discomfort of the eyes and neck or the wrists. Workstation components that are easily adjustable will help to eliminate this type of a conundrum. Ergonomics has been called the science (or art) of fitting the task to the person, and, so, adjustability is what makes office ergonomic components truly ergonomic. A workstation that can be adjusted to meet the needs of a greater percentage of the population than another workstation can be considered to be the more ergonomic.
The range of the chair’s seat height should allow the worker to set it so the thighs can be approximately parallel with the floor. Not everyone will be 100% comfortable with their upper legs parallel with the floor, but this is an ecumenical and anatomically neutral starting point for many people and should be achievable. The chair’s seat height should allow for the worker’s feet to be flat on the floor. If the feet can’t reach the floor, then the legs won’t be properly supported; they’ll be held aloft by the seat pan. The pressure placed on the upper legs at the point of contact with the seat pain could cause discomfort and impair blood circulation. This problem can also be avoided by the use of a footrest, which will support the legs. Some footrests are also adjustable.
The range of the chair’s seat height should also allow the user to be at the proper height in relation to the monitor; generally speaking, a good starting point is to have the top of the monitor at approximately the same height as the eyes. Some chairs incorporate an adjustable tilting seat pan for further comfort and positioning. The backrest height should also be adjustable.
A lower back adjustment for lumbar support is available on some chairs and is a great feature since so many seat-related problems involve the lower back. Arm rests with adjustable height will allow the elbows to be at approximately 90 degrees, which is a neutral position. Elbows shouldn’t be too far out laterally from the torso; the farther away from the torso they get, the farther they will be from a natural position and discomfort and strain will result. Having the elbows close to the torso is preferred, but they do not have to be pinned to the rib cage. If the arm rests are also laterally adjustable, then the worker can have support for their arms while also be in a comfortable position suitable to their particular body shape. It is not necessary that the arm rest provide all of its support at the elbows; spreading out the surface contact area helps to reduce discomfort and allow for more flexibility in positioning. To this end, some arm rests tilt like tilting seat pans, helping to support all of the arms while allowing workers to be more comfortable in their seated positions. And, this is the goal of ergonomic office workstation components, to be as adjustable as possible to suit the greatest number of workers as possible.
On Demand Ergonomics Webinar - Sitting Disease and Ergonomics: Evidence & Best Practice Solutions
Keyboards, Mice, and Wrists
There is a lot of bio-mechanical hardware in our wrists that allows our hands and fingers to do what they need to do; all this hardware is squeezed into a small space and is relatively prone to damage when abused. Just think of all the bones, tendons, muscles, and blood vessels that make the versatility of our hands possible. Some simple precautions can help to avoid the onset of MSDs affecting the wrists. A keyboard should be located on the desk so the elbows are at roughly 90 degrees and the wrists are as straight as possible when using it. If the desk and keyboard are too high, then the worker will need to raise the elbows to reach and this will strain the arms and also the shoulders. If the keyboard is too low, then the arms will be angled downward to reach it and the wrists will likely be bent upward while using it, which should be avoided. The mouse should be positioned close to the worker’s side and at a height where the arm will hang naturally; the arm shouldn’t be held up in an unsupported manner. As with a keyboard, the wrist should be straight as possible.
When moving the mouse around, it is ideal to have the arm and shoulder do most of the movement and not by keeping the arm stationary and bending the wrist to make mouse movements. A keyboard and mouse rest, such as a gel pad, can help to keep the wrists straight, but this should not automatically be the first option selected when dealing with wrist pain. The rest itself will result in pressure being applied to the surface area of the wrist resting on it and possibly impair blood circulation and cause discomfort. Generally speaking, if the surface of the desk is the same height as the worker’s elbows, then the wrists should be fairly straight when typing and using the mouse, and a rest may not be necessary. A simple chair adjustment to get the elbows into position to keep the wrists straight is a better first option if it allows a natural position that can minimize discomfort. If this works, then it should be preferred to incorporating keyboard and mouse rests and pads for the wrists; adding components complicates things and makes it more difficult to determine which component in the overall positioning scheme is the most responsible for discomfort and the onset of MSDs.
Much of the common guidance for workstation ergonomics addresses chairs, keyboards, and mice. And, it should. MSDs of the lower back and wrists are very common and their frequency can be reduced by following ergonomic guidelines for those workstation components. But, MSDs involving the cervical vertebrae of the upper spine and all sorts of problems involving the eyeballs are also common.
Assume there are imaginary laser beams coming from the eyeballs that illustrate a worker’s line of sight. Ideally, the laser beams will be roughly perpendicular to the spine. First, that means the cervical vertebrae in the neck should be in line with the spine, which is good. Second, that means the eyeballs aren’t peering up or down too much; they’re in a neutral position. Neutral is good. To illustrate this, relax your eyes and close them for a few seconds as if you were going to take a nap in your office chair, which is a common side effect of reading ergonomics articles. When you open your eyes, the line of sight you have is due to the neutral and natural position of the eyeballs. If what a worker looks at for 10 to 12 hours per day or more can be positioned within that general line of sight, then perhaps eye discomfort and the frequency of headaches can be minimized. A focal point slightly below the height of the eyes results in a natural, neutral, and comfortable position and this is why it’s advised by ergonomic gurus.
To test this, read some text that’s slightly above the height of your eyes while keeping the neck’s position fixed; move only your eyes to track the text. Then, rest your eyes for a minute or so. Next, do the same thing but with the text position slightly below a horizontal plane with your eyes. Notice a difference in eye comfort or strain?
Another way of illustrating this is the typical line of sight while walking. Most humans do not walk down the street with their necks and eyes oriented so their imaginary eyeball laser beams are 100% perpendicular with the ground; most have a line of sight that is slightly below a horizontal plane with the eyes. As humans evolved, avoiding trip hazards was very important to survival. So, a line of sight a little below the horizontal plane with the eyes allowed a good scan of the horizon ahead and superb focus on the ground far enough in advance to avoid stepping on a wolverine or falling into a hole.
For the reasons above, a very common guideline for monitor placement is to have the top of the monitor roughly level with the eyes; almost everything viewed in such a position will be slightly below eye height. The focal distance is also very important; 15 to 25 inches from the eyes is a good starting point. When using multiple monitors, or other viewed materials in conjunction with a monitor, the difference in their distances from the eyes should be minimized to reduce discomfort and the onset of headaches from continuously refocusing the eyes.
The aforementioned guidance is standard fare for office ergonomics. But, everyone is different and one person’s comfortable position may not work for another. But, there is something that everybody can do; move around! With all the adjustments built into modern workstation components, a person should be able to find a number of comfortable positions that work for them. Even slight and seemingly insignificant postural changes can be helpful when done frequently to avoid sitting in the exact same posture for half a day.
Even when a person is seated comfortably and has followed every available ergonomic guideline for seated work, the fact is that seated work is still sedentary, bad for overall health, the cause of many MSDs, very costly to employers’ financial health, and relatively just evil. The best case scenario for seated work will minimize the degree to which overall health is damaged, but it still takes a back seat to standing, pun intended. So, getting up from the chair as much as possible is well advised. Getting up to shake off the ills of chairdom for a minute or two every 20 minutes or half-hour isn’t exactly a fitness class, but it does get the joints moving and blood flowing. If the phone cord is long enough or if a mobile phone in the office is the norm, standing up during calls is a good way to guarantee some standing time.
There are lots of office tasks that one can do while standing to condition oneself to be on the feet as much as possible; every workplace is different and opportunities should be explored. Coworkers may look at you weird when they see you pacing around your cubicle and wonder what’s going on, so feel free to tell them why; maybe others will start standing more. Sitting at a workstation isn’t ideal, but this mode of work isn’t going away anytime soon.
On Demand Ergonomics Webinar - Sitting Disease and Ergonomics: Evidence & Best Practice Solutions
Written by Maurizio Delcaro
Maurizio believes that a commitment to operational efficiency at all levels of management is the greatest factor in maximizing safety and productivity. His EHS and risk management experiences include transportation, construction, environmental remediation, and OSHA, and he moonlights as a part-time university instructor. Maurizio is credentialed as a CSP, CET, OHST, and CHST with the Board of Certified Safety Professionals and CEHT with the National Environmental Health Association.