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Sit Up Straight

In the last issue of Lab Manager, we began to explore the ergonomic risk factors associated with the use of
computers. To recap briefly, three of the fundamental ergonomic risk factors are: position/posture, repetition/duration, and force. These can all be influenced by the work area setup and the activities being performed.

Vince McLeod, CIH

Vince McLeod is an American Board of Industrial Hygiene-certified industrial hygienist and the senior industrial hygienist with Ascend Environmental + Health Hygiene LLC in Winter Garden, Florida. He has more...

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Laboratory Ergonomics - Part 2

The good news is, these risk conditions that may cause pain and potential injury can often be easily controlled if one understands basic ergonomic concepts and how to apply them.

In our first part of this series, the take-home message was “balanced” and “neutral.” In a nutshell, our basic rules are summarized as follows:

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  • Your monitor should be directly in front of you with the upper edge of the screen at eye-level or slightly below.
  • Any hardcopy you work from should be placed in front of you on a document stand (not on the desk at your side) either between the keyboard and monitor or immediately to the side of the monitor.
  • The keyboard and mouse should be in front of you and generally as close as is practical to prevent overreaching.
  • Your wrists should be straight in both the vertical and lateral axes.

In this issue we will discuss repetition/duration and force as they apply to ergonomic risk in the office setting, as well as some possible solutions to get you through the day pain-free.

Repetitive motion

Repetition by definition involves doing things over and over again. In repetitive work, these same types of motions are performed using the same parts of the body in the same fashion, time and time again. In activities such as typing, using a mouse, or referencing paper source documents, the affected muscles, tendons, and joints can be used thousands of times a day, week after week, year after year. The risk of injury is even greater when repetitious jobs involve awkward posture (e.g., bent or flexed wrists) or forceful exertions such as repetitive overreaching for the mouse (shoulder and neck pain).

Now, in conjunction with a posture that is neutral and balanced as discussed in Part 1, our goals from an ergonomic standpoint are to reduce the number of repetitions experienced by each set of muscles, tendons, and joints throughout the workday and to allow time for recovery. The body has great capacity to repair itself. Problems arise, however, when the amount of damage or stress accumulated over the course of time outpaces the body’s ability to repair. This is when we experience pain, and if the cumulative damage continues, there is the potential for serious injury.

Short breaks in repetitive tasks can be of significant benefit. Break up data entry with variations in activity such as filing, reading, using the copier, or any other task that uses different muscles and motions than computer use. It is good to include micro-breaks of just a minute or two every half hour or so during data entry campaigns. There is good software now available that tracks keystrokes and mouse movement and alerts you when breaks are appropriate. It is often better to take many small breaks than one long break during the workday.

It is important to examine and analyze the work being performed. Look at this along the same lines as a job hazard analysis, where the parts of the job are examined on a task-by-task basis. In many cases we have seen, there is much unnecessary repetitive work because of poor process design (or because the process was really not designed at all—it just grew). Questions that should be considered include: Can parts of this process be automated? Can equipment be linked directly to CPUs for data collection? Can databases be programmed to “talk” to each other? In some instances, perhaps, bar codes and readers might be used to reduce data entry; in other types of information collection and entry, readable/scannable forms might be appropriate. It is often well worth investing a little time to engineer a solution that will save significant time and effort in the long run.

Often we can trace pain to mouse overuse, typically combined with poor mouse location. Directing the conventional mouse requires a great amount of work through one arm, shoulder, and hand. It is often best to try to distribute this work and share it between both sides. One approach is to use keyboard commands instead. For those of you who remember those keyboard commands from the DOS days, most of them still work. For example in Windows, Ctrl-A will “select all,” Ctrl-C can be used to copy text and Ctrl-V will paste. Look at the menu bar at the top of your document next time you are at the computer; all the selections have one letter underlined (e.g., File, Edit, View, Table). If you hit Alt and the underlined letter, the drop-down menu will expand just as if you mouse-clicked on it. Ctrl-underlined-letter on the commands in the drop-down menu will perform that function. This can greatly reduce mouse use and, once you get familiar with the keyboard commands, actually speed up your work.

There are now at least a couple of “alternative mice” that place the tracking device between you and the space bar. This allows one to use both hands for mousing, sharing the work between them.

Some software programs also allow you to automate common tasks (such as inserting your address) with scripts called macros. These can significantly reduce the amount of typing you need to do.

Forceful exertion

Force is the amount of muscular effort expended to perform work. Exerting large amounts of force can result in fatigue and contribute to injury. The amount of force exerted depends on a combination of factors, including:

  • The effort with which one strikes an object (e.g., pounding the keyboard)
  • The shape and dimensions of an object you are working with
  • How you grip an object or tool
  • The preciseness of motion required to do the task
  • The duration of force applied by the muscles (e.g., the amount of time spent without a muscle-relaxation break)
  • Awkward postures (overreaching)

In addition to pounding the keyboard, some areas where unnecessary force is applied are in writing and filing/shelving. There are two general types of grips people use; a “pincher grip,” where you press your finger against your thumb, and a “power grip,” like you would hold a suitcase. The pincher grip requires much more force and should be avoided when possible (e.g., instead of pulling large files out of a cabinet by grasping with a pincher grip from the top, slide your hand beneath the folder and lift it from the bottom using a power grip).

People often use quite a bit of force while holding those standard skinny pens and pencils. Because writing is precise work (after all, you must be able to read what you write), there is some resistance between the writing surface and your pen. The difficulty in gripping a thin barrel is that you must hold it tightly to maintain control. Much better are those wide-barrel pens and mechanical pencils with the soft grip at the end. One does not need to grip nearly as hard, thereby reducing strain on the muscles and tendons. Personal preference does come into play here, so you might audition a couple of different types of pens to see what feels most comfortable to you. Try to hold the pen as loosely as is practical yet still maintain control.

Despite efforts to both reduce the repetition or duration of your exertion and reduce the force applied to perform a task, there is not usually a single “golden bullet” that will be a panacea for one’s ergonomic woes. OSHA provides an excellent review through its eTool on ergonomics.1,2 The State of Washington also has some very good self-evaluation checklists and guides.3 One has to recognize and be cognizant of reducing all these risk factors both on and off the job to effectively reduce the potential for pain and injury.


  1. Prevention of Musculoskeletal Disorders in the Workplace, U.S. Department of Labor, Occupational Safety and Health Administration. Washington, D.C. 
  2. Computer Workstations, U.S. Department of Labor, Occupational Safety and Health Administration. Washington, D.C. 
  3. Office Ergonomics, Washington State Department of Labor and Industries. Tumwater, WA.