(Adapted from Repetitive Strain Injury by Dr. Emil Pascarelli and Deborah Quilter)
In simple medical terms, repetitive strain injury (RSI) is defined as a cumulative trauma disorder (CTD) stemming from prolonged repetitive, forceful, or awkward hand movements. The result is damage to muscles, tendons, and nerves of the neck, shoulder, forearm, and hand, which can cause pain, weakness, numbness, or impairment of motor control.
You may wonder how seemingly innocuous activities such as typing and clicking a mouse button could possibly be harmful. Fine hand movements, repeated hour after hour, day after day, thousands upon thousands of times, eventually strain the muscles and tendons of the forearms, wrists, and fingers, causing microscopic tears. Injured muscles tend to contract, decreasing the range of motion necessary for stress free work. The sheaths that cover delicate tendons run out of lubrication because they aren't given time to rest, so tendon and sheath chafe, resulting in pain. Due to this abrasion, tendons become inflamed, and begin to pinch neighboring nerves. This can result in numbness, tingling, or hypersensitivity to touch. Unless this cycle is interrupted, it repeats itself over and over, and a long-term, chronic problem results.
Repetitive strain injury can affect more than just your hands and wrists. Poor posture can lead to severe neck and back injuries. Staring at a computer screen can lead to eye strain. Repetitive reaching for a mouse can lead to arm and neck strain as well as spinal asymmetry.
RSI is not a specific medical diagnosis, but rather a family of disorders. Many people mistakenly equate RSI with carpal tunnel syndrome, even though CTS is only one particular form of RSI. One recent study even reported that frequent computer users are no more likely to develop CTS than non-computer users. Don't let this mislead you, though. Many other forms of RSI do come on as a result of frequent computer use.
Who is at risk?
The three primary risk factors are poor posture. poor technique. and overuse. These topics are discussed in depth in the section on prevention. In addition to these, there are several other risk factors to be aware of. While they may not cause RSI on their own, they can increase your risk if you already possess one of the three primary risk factors. The following list (adapted from Pascarelli and Quilter ) lists several risk factors. You may be at risk for developing an RSI if you:
- Have poor posture
- Have poor technique
- Use a computer more than two to four hours a day
- Have a job that requires constant computer use, especially heavy input
- Don't take frequent breaks
- Are loose-jointed
- Don't exercise regularly
- Work in a high-pressure environment
- Have arthritis, diabetes, or another serious medical condition
- Keep your fingernails long
- Have an unhealthy, stressful, or sedentary lifestyle
- Weigh more than you should
- Don't sleep well
- Are afraid to ask for better accommodations
- Won't accept that you are at risk when you really are
Consult Pascarelli and Quilter for further information.
What are the symptoms of RSI?
The primary warning sign of RSI is pain in the upper extremities (fingers, palms, wrists, forearms, shoulders). The pain may be burning, aching, or shooting. It could be local (e.g. fingertips) or diffuse (e.g. the entire forearm). The pain will typically be increased after a long session of computer use. Keep in mind, however, you can have severe RSI without experiencing pain. The following checklist (adapted from Pascarelli and Quilter ), can help you determine whether you have RSI:
Do you experience:
- Fatigue or lack of endurance?
- Weakness in the hands or forearms?
- Tingling, numbness, or loss of sensation?
- Heaviness: Do your hands feel like dead weight?
- Clumsiness: Do you keep dropping things?
- Lack of strength in your hands? Is it harder to open jars? Cut vegetables?
- Lack of control or coordination?
- Chronically cold hands?
- Heightened awareness? Just being slightly more aware of a body part can be a clue that something is wrong.
- Frequent self-massage (subconsciously)?
- Sympathy pains? Do your hands hurt when someone else talks about their hand pain?
In addition to these symptoms, RSI can also lead to behavioral changes. You may not even be aware of these changes. For example, do you:
- Avoid using the injured hand?
- Use your nondominant hand more frequently?
- Use your forearm, feet, or shoulder to open doors?
- Avoid wearing or buying certain kinds of clothing because it is too difficult to put them on?
- Change shopping habits because you can't carry as much as you once could?
- Keep dropping things?
- Find you can't chop food?
- Not play sports you once enjoyed?
- Have trouble hooking bras or putting on jewelry?
- Not wear bracelets because your wrists are tender?
- Have trouble with keys or brushing teeth?
- Feel overly protective of your hands?
Repercusions of RSI
If you develop RSI, and do not take steps to correct the problem, there may be serious repercussions. When my RSI was at its worst, I was unable to open doors, prepare my own food, do laundry, drive, write, type, and shake hands. This lasted for half a year. I was unable to type regularly for about three years. Many RSI sufferers complain of similar problems. In addition to limiting your day-to-day functionality, this decreased independence can cause a significant emotional burden.
RSI can limit your ability to perform at work. Recent Supreme Court rulings do not view RSI as a disability, and hence, RSI is not covered under the Americans With Disabilities Act. (Apparently typing is not a "major life activity," according to a recent opinion authored by Sandra Day O'Connor, for those whose job requires significant amounts of typing.) Therefore your employer may fire you if you are unable to perform your job because of your RSI. The prospect of changing (radically, in many cases) your profession is obviously a daunting thought. For students, most universities are willing to make accommodations, but lost productivity due to RSI could still delay your graduation one or two years. And once you graduate, your next employer may not be as accommodating.
As with all health-related issues, it is wise to eat well, exercise, listen to your body, and avoid destructive behavior. However, there are some specific precautions you can take to help prevent the onset of RSI.
When you first notice symptoms of RSI, you have already done substantial damage to yourself. RSI can take months, even years to develop, and you can expect it to take at least twice as long to heal. It has been several years since my RSI was at its worst, and even now I must limit my typing. Even if you feel no pain or other symptoms of RSI, you would do well to heed the following advice for RSI prevention, especially if you meet one of the risk factors outlined above.
Good posture is crucial
What is good posture? For our purposes here, good posture is when you are seated in such a way that the effort required to work at your computer is minimized. The following checklist identifies the proper way to sit in order to achieve good posture:
- Feet: flat on the floor
- Knees: directly over feet, bent at right anlges (or slightly greater), with a couple inches of space from the chair
- Pelvis: rocked forward, sitting on the "sitz bones," with hips (the sockets where your femurs attach) positioned no lower than, and perhaps slightly higher than the knees.
- Lower back: arched in, and possibly supported by your chair or a towel roll.
- Upper back: naturally rounded
- Shoulders, arms: relaxed, at side.
- Neck: arched in, relaxed, supported by spine. Be careful not to hold tension in back or under chin.
- Head: balancing gently on top of spine.
There can be exceptions. For example, it's OK to shift your legs and feet around if they get figgety, but be sure to always keep the spine neutral and the head balanced above the pelvis.
Unfortunately, the above written description can be very difficult for some people to actualize. Over the course of our lives, our bodies become so habituated to certain patterns of muscle tension, that we are unable to accurately perceive ourselves. For example, I may feel like my spine is in a neutral position, when in fact my lower back has too much arch. Even if I were to show you pictures, that would not solve the problem because (1) the difference between good and poor posture can be subtle, and (2) even if I could perfectly describe proper posture to you, your brain may not have the ability to accurately put your body in that position, because of the aforementioned habitual patterns. One solution to this dilemma is to have a skilled teacher re-educate you on postural awareness. This can be done by someone trained in a form of "bodywork" such as the Alexander technique. Another strategy is to
regularly practice gentle yoga or other practices that enhance mind-body awareness.
I believe that your posture at your workstation is the most important factor in determining your risk for RSI. Moreover, in my experience, your chair is a major determinant of your posture. I cannot overstate this. Sitting at a workstation entails holding your body in a static position (described above) for long periods of time. Holding yourself in this position puts strain on your muscles. The less support you receive from your chair, the more strain is placed on your body. Therefore, it is essential to have a chair that supports you as well as possible.
The key to a good chair is adjustability. A good chair will be adjustable in the following ways:
- Height of seat
- Angle of seat
- Height of backrest
- Angle of backrest
- Seat slides forward or backward
- Arm rests move up/down and in/out
It is also important to have a firm seat, so that your pelvis can be firmly grounded, but not too firm, so that your rear isn't killing you after a short time. Be careful to avoid chairs with a bucket seat, i.e. a seat that makes your pelvis rock back. Tall people will prefer a chair with a high backrest. A head/neck rest should not be necessary, since your head should be balanced over your spine. Wheels are also nice, if you have a carpeted floor, although wheels on a wooden floor may slide around too much. The seat pan should be long enough such that the space between your calves and the end of the seat pan is about two finger-widths. If you are tall, you may need a chair with an extra long seat pan. For my back, I sometimes use a support called TruComfort. which I have found to be very helpful.
Highly adjustable chairs can be expensive, costing several hundred dollars. I got my chair at a discount (
$700) through the Ergonomics Office at my university. Check with your employer's ergonomics office, to see if you can receive a similar discount. If you can afford it, a good chair is definitely worth the investment, and the higher the quality, the longer it will last you. A well made chair should last 20 years or more. But be careful when purchasing a new chair: many models say they are ergonically designed, but are not. Be wary of less expensive models sold at box stores; you will get what you pay for. I recommend that before you buy a chair, you do two things: (1) Use the chair for a week to make sure it fits you (your ergonomics office may have a loaner program.), and (2) read Sitting at Your Computer .
Another option is a standing desk. You'll want to be able to move back and forth between standing and sitting, so you need a height-adjustable desk (preferably electric powered), or a contraption that sits on you desk and can raise up, like this one.
If your company has an ergonomics office, they likely employ an occupational therapist who can come to your office and help you set up your workstation.
Setting up your workstation
There are three pieces of equipment that require special attention:
- Keyboard. positioned above your thighs, you shoulder be able to reach the keys with your elbows at your side and bent at 90 degrees, and your forearms roughly parallel to the ground. If your elbows are at more than a 90 angle, it will surely tire you out quickly.
- Mouse. just to one side of your keyboard, so that you don't have to lean, stretch, or hunch to work it. Many people have one shoulder noticeably lower than the other - this can be caused by repetitive stretching for a mouse;
- Monitor. directly in front of you (not off to the side), such that your eye level is somewhere between the top of the screen and 20% from the top. The screen should be about 15-25 inches from your eyes.
This last point is very important, but can be problematic if you only have one desk, and like space to write. In this case, I suggest one of three possibilities: (i) Find another place to write, such as the library; (ii) Get a cheap computer desk if you have room in your office; (iii) Find a rolling or sliding tray to put your monitor on, so you can move it aside when you need to write. If you don't position your monitor correctly, it can lead to severe neck strain over time. For example, if your monitor is too far back on your desk (or if your font is too small), you will have the tendency to hunch forward and jut your head out, in a subconcious effort to see the screen better. This leads to another key point: Don't use really small fonts. It leads to poor posture and eye strain.
If you use a laptop, you will find it is vitually impossible to use good posture. This is why I strongly recommend against the use of a laptop as an everyday computer. I used a laptop all through college, and I know it contributed to my RSI. If you do most of your work on a laptop, you really need to find a separate keyboard so that you can put your laptop on a box or some books, and have your monitor at eye level. You could alternatively find a separate monitor, but laptop keyboards tend to be too small. Another novel solution is the lightweight and highly portable Roost Stand .
Proper technique: typing, mousing, and writing
There are three keys to proper typing technique.
- Keep your wrists straight. the straighter your wrists, the less strain you put on the tendons and nerves that run through your wrist. A split keyboard may aid you in keeping your wrists straight.
- Let your hands float. This means don't rest your wrists on the desk, keyboard, or a wrist rest when you are typing. Let them hover over the keys. This has three advantages: (i) You allow the big muscles in your back to share some of the work; (ii) It allows you to keep your wrists straight, which is impossible if they're planted on a wrist rest; (iii) It's easier to reach the hard-to-reach keys (next item).
- Don't strain your fingers. When you need to press a hard-to-reach key, like CTRL, SHIFT, BACKSPACE, etc. don't stretch out your pinky. Instead, move your whole hand and use your index or middle finger to press the key. Don't use one hand when you need to hit two keys simultaneously, e.g. CTRL-X, SHIFT-Y. Think before you type: unnecessary retyping/editting can add up. Use a light touch when typing: don't pound the keys.
An ergonomic posture reminder that you can post near your computer was created by Clemens Conrad.
There is another keyboard layout, in addition to the standard QWERTY layout. Called the Dvorak layout, it was designed to minimize the movement of your fingers as you type. In contrast, QWERTY was designed to maximize the amount of finger movement, so as to avoid jammed levers in old mechanical typewriters. Most operating systems allow you to switch your keyboard to this format (in Windows, try Control panel -> Regional and Language Settings -> Languages -> Details). When I switched to the Dvorak layout, there was about a month of transition time where I wasn't able to type as fast as I used to. Now, I have less pain in my hands than before I made the switch. You can find Dvorak typing tutors online.
In addition to Dvorak, there is yet another layout called Colemak that is designed to improve upon Dvorak. For example, Dvorak has the "s" and "l" letters typed by the right pinky which puts execive strain on this digit. It is not currently standard in operating systems like Dvorak is, but you can download the software from the link above.
Using a mouse can be even more harmful than typing. Here are three reasons why this is so:
- All the work is done by one finger. Double clicking and dragging can be especially straining.
- Modern windows-based machines rely heavily on the use of a mouse.
- Users often do not position the mouse properly. Instead, they stretch for the mouse, which can lead to increased strain, a drooping shoulder, and pain extending up into the shoulder and neck.
My solution for these problems has been to switch to a trackball. This has the advantage that the mouse is stationary: you don't have to move your whole arm to move the pointer across the screen, which reduces strain on the arm, shoulder, back, and neck. It also has extra buttons, which can be programmed to double-click or drag with a single click. Moreover, the work is more evenly distributed among the fingers. Actually, I have two mouses. One is a trackball on the left, and the other is a standard mouse on the right that I use for scrolling and moving but never clicking.