This article is reprinted with permission from The Ergonomics Report™ Archives, where it originally appeared on March 14, 2012.
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The 1980’s and 1990’s were a time of rapid growth in the use of personal computers and a time of significant increases in reports of what are often called Repetitive Strain Injuries (RSI’s – now typically called Musculoskeletal Disorders or MSD’s in recognition that there are more risk factors than repetition alone that can contribute to discomfort, pain or injury). Naturally, it was assumed that the proliferation of computers in the workplace was the cause of increased injuries.
In 1980 there were an estimated 5 million computers in the workplace. That number increased to 40 million by 1990. Concurrently, MSD’s climbed steadily until they peaked in the mid 1990’s.
Computers have continued to proliferate in the workplace while the number of MSD’s has declined. In 2009 the US Census Bureau reported that nearly 300,000,000 Americans had Internet access, and a 2008 report by Forrester Research showed that there were over one billion computers in use worldwide. Meanwhile, the US Bureau of Labor Statistics reported that overall MSD’s have declined from approximately 400,000 cases in 2004 to 284,000 cases in 2010.
Causes of the Problem
There has been much discussion and debate about the causes of the MSD problem. Some early studies implicated things like faulty keyboard design and the repetitive nature of computer work as the main causative factors in the MSD problem. Others explanations were also proposed such as these from a 2008 The Ergonomics Report™ article written by William Hargreaves:
It isn’t clear whether the sudden rise in RSIs was due to greater awareness of worker health inside businesses, or was due to reporting changes. Another possible cause was a sudden change in the pace and work habits of the American work force … [which]… was certainly true for office workers. Dramatic changes were occurring in both work habits and methods in the same time period that their RSIs began to increase. …Many people believe that this explosion of computer use led to the explosion in office RSI.
Solutions to the Problem
While the MSD problem has improved, there continues to be debate over specific causative factors and effective interventions. A recent comprehensive review of the literature published between 1999 and 2010 came to these conclusions:
- There is moderate to high quality evidence indicating an increased risk of acute or transient pain complaints among computer users, when they are keying or using their mouse intensively, but a causal relation is still uncertain.
- There is no evidence for specific diseases or chronic pain development.
- There are no effects of preventive interventions that include only workstation adjustments.
- There is limited evidence that a combination of ergonomics training with workstation adjustments may be beneficial.
What can practitioners do?
While the current state of evidence is not strong for any particular ergonomic approach to deal with computer-related discomfort and MSD’s, many of us are called upon to assist users with problems. We need to rely on conclusion #4 above and rely on a combination of ergonomic training and workstation adjustments as our best bet. Here is a protocol I’ve developed after 20 years of work in call centers and in a chronic pain rehab facility:
Use a combination of work practice and workstation adjustments to address the common office ergonomics Risk Factors of awkward postures, static postures, excess force, repetition, and insufficient rest.
1. Keyboard placement:
- Place the keyboard low enough so the shoulders are relaxed and there is minimal pressure on the wrists. Most standard work surfaces are too high for keying and many users need to either raise their chairs or lower the keyboard.
- Place the keyboard and mouse close enough to limit reaching. If the user chooses to reach out ensure that there is comfortable support to rest the hands and arms.
2. Keyboard use:
- Align the keyboard with the forearm (adjust tilt legs), and use a “wrist rest” where appropriate to reduce wrist extension or bending back (better termed as a palm rest so as not to give the impression that users should rest/apply pressure to their wrists). If the keyboard is low it should generally be placed flat or on a negative/downhill tilt to keep the wrist straight.
- Use relaxed hand postures — keep the fingers curved, avoid tense extended fingers, and don’t stretch fingers out to reach distant keys.
- Move the whole hand — leave the home row to click distant keys such as tab, delete, enter, etc. Avoid side bending of the wrists to reach keys.
- Use a light touch — many users apply too much force when keying. A light touch is all that is needed to activate most keys.
- Find and use a comfortable place to rest the hands and arms. Remove the hands from the keyboard and mouse when pausing to read, think, listen, talk, etc. Rest the hands on the pinky side with fingers curled and thumbs up.
- Break up repetitive work. Try to alternate between computer and non-computer tasks that use different muscles if possible. At a minimum, alternate between intensive input work and less hand intensive information retrieval work if possible.
3. Mouse use:
- Move the whole arm, not just the wrist. Mouse as if washing a dish, not side to side like a windshield wiper.
- Release the grip. Static, unrelenting grip on the mouse increases muscle tension and reduces blood flow. Take the hand off the mouse when not actively using it.
- Learn and use keyboard shortcuts. These often involve only one or two fingers (as opposed to five fingers for the mouse) and can often be performed with a straight wrist. Shortcuts can also be faster than mousing.
4. Consider a keyboard with one or more of these ergonomics related features:
- Some keyboards are split or bent in the middle to limit side-to-side wrist bending. Many times they are also “tented” or raised in the center to limit inward twisting or pronation of the arm and wrist. These ergonomic features allow a more neutral wrist position while working.
- Some keyboards are adjustable in the amount of side-to-side split and central tenting. This allows personal adjustment necessary for some users, and allows the use of central pointing devices such as the Rollermouse, the Trackbar, or a touch pad. Many users, however, will do just fine with the fixed split keyboards characterized by a prominent curved palm rest.
- Some keyboards have separate or detachable numeric keypads, which can be removed to allow closer mouse placement. This can reduce reaching to the mouse, which is helpful particularly for smaller people with narrow shoulders.
- Some keyboards have dished keypad arrangements to allow the fingers to naturally drop down helping to keep the wrist straight and the hand relaxed. Such designs may also reduce finger reaching distances.
- Some keyboards have an imbedded central mousing device such as a touch pad or a trackball which can be a nice benefit if you have a limited space for a traditional mouse, or if you prefer central mousing, like me.
- Other varieties of keyboards include those with more desktop adjustment for tenting or central tilt, keyboards that come in two parts and attach to your chair armrests, and “chord” keyboards that use combinations of keystrokes rather than individual letters for spelling.
5. Consider a mouse with some of these ergonomics related features:
- Slanted or tilted somewhat upright to limit inward twisting or pronation of the forearm.
- Shaped and sized to comfortably fit your hand with fingers in a natural curved position. Avoid a mouse that doesn’t fit or forces your fingers into a splayed or spread out posture.
- Possibly try a central pointing device that places the mouse control right in front of you. Many versions are built into the wrist rest and allow easy reach, relaxed shoulders, and bi-lateral use of the hands.
- Continue to learn and use keyboard shortcuts. Clicking a key is often easier than mousing because it is a stationary target and only requires one or two fingers to activate.
- Move and change positions. The human body does best with a variety of tasks and a variety of positions. Dynamic is better than static.
Comfort by Design: Selecting an Ergonomic Keyboard, The Ergonomics Report™, August 6, 2008, William R. Hargreaves, Ph.D.
Risk factors for neck and upper extremity disorders among computers users and the effect of interventions: an overview of systematic reviews. Andersen JH, Fallentin N, Thomsen JF, Mikkelsen S. At the time of this writing this article was available free of charge at Pub Med: http://www.ncbi.nlm.nih.gov/pubmed/21589875
This article originally appeared in The Ergonomics Report™ on 2012-03-14.