Repetitive Strain Injuries (RSIs) sometimes referred to as Cumulative Trauma Disorders (CTDs), have been
around for decades. Long before computer terminals and their keyboards were ever created. They have existed
in the industrial environment, where numerous functions require the constant movement of the fingers, with
varying degrees of exertion.
The wrist RSIs or CTDs that sometimes develop, carpal tunnel syndrome, tendonitis, etc. have been continuously studied and usually found not to be caused by what people did, but by how it was done.
Wrist pain is the usual warning at a potential RSI problem exists and task modification or instructions on maintaining a straight, hand in-line to the wrist position where possible, is the accepted preventative measure in the industrial environment.
Applying this knowledge to the office environment, it must seriously be considered that using keyboards is not the problem, but how the keyboard is used.
Why is it that typists did not have RSI problems? Quite probably it was because as part of their initial instruction, typists were taught how to sit in an upright posture, and how to position their hands. The problem is not that keyboards require too much pressure, typewriters always required more. In fact, part of the problem might be keyboard sensitivity. Remember this?
Typewriter keys were sufficiently resistant to the touch that users could rest their fingers and to some degree the weight of their hands on the keys. On keyboards, they cannot. When you combine keyboard sensitivity with the improper posture most people are sitting in, you are laying the groundwork for an RSI to develop.
Too many people sit in their chair leaning back. Sometimes this posture is forced by poor chair design but more often the person has not properly adjusted the chair they have. When an individual keys while leaning back, their arms must be held suspended in front of their body. A function for which the human body is poorly designed.
Fatigue soon develops and the next thing that happens is keyboards are pushed back from the front edge of the supporting surface and wrists are dropped into a resting position in front. Or people simply press the heel of their hand against the surface supporting the keyboard, if its depth doesn't allow for the keyboard's movement. Either way, the hand is now deflected, stretching the tendons and ligaments and pressing the nerves. Again, it is not what people do, but how it is done.
Does that mean that if the user had maintained proper hand position to begin with, they would not have required the brace?
A January 1992, article in the Toronto Star titled, "When Work is a Pain", included the above photo, showing a person keying with a brace on their right wrist. The article focuses on wrist and hand RSIs as some of the potential problems keying can cause, and the writer obviously wants us to focus on the encased wrist in the photo, to appreciate just how severe the injuries can become. But what we SHOULD be looking at is the persons LEFT hand and wrist.
Clearly the heel of the left hand is pressed against the surface supporting the keyboard, causing the hand to bend backwards and the fingers to arch over into a keying position. This person will soon require a brace for their left wrist, but it will not be because they key a lot, as much as it will be for how they key.
Wrist supports or palm rests can virtually eliminate all wrist pain and the potential for an RSI to develop, but only if they are utilized properly, and other steps are taken as well. People must first make sure their chair is correctly adjusted. At a proper seat height, the thighs will be parallel to the floor, for an even distribution of weight. Chair backs must be independently adjustable, to firmly support the lower back when the user is sitting in an upright posture.
However, if you are somewhat taller or shorter than average, taking these steps with your chair will be pointless; if all surfaces in your workstation are not also adjustable.
How does all this lead to a Repetitive Strain Injury or a Cumulative Trauma Disorder?
Keyboards that are too high cause the user to 'shrug' to maintain a proper keying position, using the muscles across the top of the shoulders and up the neck, to support the weight of both the upper and lower arm.
In fact over the 14 years that we have been planning and implementing workstation solutions for computer terminal operators, we have found the discomfort and pain this ,shrugging' causes, to be more prevalent than wrist pain. That is because most keyboard support surfaces are simply too high for the employee. Many people who drop their wrists or palms onto the surface supporting the keyboard, are actually seeking to relieve this discomfort, which then makes them a prime candidate for an RSI.
Leaving the keyboard too high but adding a wrist support will actually increase the potential for an RSI or CTD to develop, as the users will drop the shrugging of their shoulders when they rest their wrists, but increase the deflection of their hand in the process. Besides, the persons wrists will be at an angle to the wrist support and if its angle is not adjustable, and it has a sharply angled edge, it will be very uncomfortable.
As long as people come in different sizes, the keyboard height must be adjustable. Then the home row of keys can be adjusted to elbow height, after the user has adjusted their chair to support a proper sitting posture. A straight, hand in-line to the wrist position can now be maintained, without shrugging.
In fact a proper keying height and correct sitting posture may reduce or eliminate the need for any kind of wrist support, especially for people with previous typing experience. They know what proper posture and hand position is and that it should be maintained.
Still, most people will benefit from a correctly utilized wrist support on an adjustable surface. Partly that is because there are far more people using terminals who are not properly trained typists, but mostly because of the keyboard sensitivity mentioned earlier.
Yet using a wrist support at the wrist, can also cause discomfort. At that part of the arm, nerves and veins are very close to the surface of the skin. Having a support at this position, especially one that is too narrow or has a peaked shape, can actually impede blood flow or irritate the nerves. Watches or bracelets can increase the discomfort, as they are pressed into the wrist at point of contact. Perhaps this is why many people actually refuse to use a 'wrist' support.
Many 'experts' suggest they should be used as palm rests anyways, with the keyboards pulled right up against them. However, anyone who has tried this, will know that can cause discomfort as well. The 'pisiform' is a prominent bone located to the outside of the hand, near the wrist. With very little flesh between it and your skin, at least for most people, it is this part of your palm that will bear most of the weight. Since standard keying requires frequent movement of the hands across the keyboard, it is not long before this bone or the skin covering it becomes quite irritated by the 'palm' rest.
People might return to pressing the heel of their hand against the surface supporting the keyboard, because at least this can be done using the fleshiest part of the hand. Of course they will remain a prime candidate for a wrist or hand RSI, but will consider themselves to be better off, at least until some pain starts to develop. At which point that individual will simply blame all of their problems on the fact that they must use a keyboard as part of their task function. Especially if they read misleading media articles on the subject.
It may seem the only answer is to encourage people to work using a wrist or palm support, even if it might cause some other discomfort. While officially taking such steps could give companies a defence in the event of being sued for a repetitive strain injury by their employees, especially if they refused to use a support provided, (and the keyboard surface was height adjustable, and the employees understood how and why to use them, and . . . ), there is another solution. Suggest keyboard use away from the support.
The further up the underside of anyone's arm pressure is placed, the less the discomfort. That is because the amount of flesh covering the nerves and veins increases. Therefore, what many people may actually require is not a wrist or palm rest, but a forearm rest.
Keyboards can be pushed as much as four, five or even six inches away from the inside edge of the support, depending on the length of an individuals forearm. This is an ideal and extremely beneficial working position for many people, but not just because of the greater comfort felt underneath the forearm. It is because the physical differences in people that must be accommodated, includes not just their heights, but their 'widths' as well. When people sit and simply drop their arms to their sides, the distance between their elbows will vary. Broad shouldered or heavy set people will have a greater distance.
However, the distance between our hands, when in the home row position on a standard QWERTY keyboard, does not vary for anyone. Because the users hands must also 'square up' in a straight line on the home row, using a palm or wrist support can increase the sideways hand deflection.
By using the 'wrist' support as a 'forearm' support, however, the sideways deflection of the hand is decreased substantially. The user is now in as close to a straight, hand in-line to the forearm position as they are likely to get. Up, down and sideways. Provided all the other steps have been taken and they have been properly trained, the potential for a related Repetitive Strain injury or a Cumulative Trauma Disorder has been virtually eliminated.
Remember, however, that most employees will be forced to compromise proper sitting and keying positions, if they must also complete desk work on adjacent, nonadjustable surfaces, or sit in chairs with fixed arms. Armless chairs work much better, especially at angled workstations. Typists never had chairs with arms, for reasons that still apply. Tiltable keyboard support surfaces are also not required in a workstation that is properly adjusted, as they will cause hand deflection if utilized. Extending the feet at the back of the keyboard is ail that is necessary to achieve a proper keying angle.
While all of these steps can virtually eliminate the danger of an RSI developing, or the wrist pain many people experience after as little as a half an hour of keying, there are many other discomfort problems affecting employees. Unfortunately, most are created by incorrect ,expert' advice and improper 'ergonomic' workstations, such as those that utilize articulating keyboard support arms.
Knowing how to determine what specific solution is required and having the proper training capabilities to ensure that each is utilized properly can be difficult, yet is essential in eliminating all of the physical discomforts and injuries being associated with using computers, but caused by the workstation. Besides, employees are hurting, and they need help, now.