Wednesday, September 2, 2009

Lab 1 – Introduction To Ergonomics


To make sure the students understand: -

  • What is ergonomics?
  • Tips for Healthy Keyboard Usage
  • Tips for Healthy Monitor Usage
  • Tips for Healthy Mouse Use
  • Example of Medical Problem Associated with Ergonomics

Objective 1: What is Ergonomics?

Ergonomics is a science whose main purpose is to design workspaces and tools that help people do their jobs and use their tools and other products comfortably and safely. One definition of ergonomics is:

"Ergonomics and human factors use knowledge of human abilities and limitations to design systems, organizations, jobs, machines, tools, and consumer products for safe, efficient, and comfortable human use."

Ergonomic design blends the best abilities of people and machines.

§ Human not as strong as machines, cannot calculate as quickly and accurate as machine

§ Machine cannot repair themselves when broke down, cannot hear or speak like human

§ Ergonomic design takes advantage of both

Primary goals of ergonomic:

“Prevention of workplace illness and accidents”

Objective 2: Tips for Healthy Keyboard Usage

1. Use a light touch when typing (don't bang on the keyboard!).

Try to use the minimum amount of force necessary to depress the keys. The tendons from your fingers connect near your elbow, so striking the keys too hard can lead to problems you might not associate with your keyboard—for example, pain and inflammation in your elbows (Epicondylitis).

2. Keep your wrists in a neutral (straight) position—not bent up or down.

Repeatedly bending your wrists up and down (extension and flexion) compresses structures inside the carpal tunnel in the wrist. This can cause pain and lead to injuries like carpal tunnel syndrome. When you're typing, your forearms tend to sag as the arms tire, putting the wrists into even greater wrist extension—another good reason to take frequent stretch or rest breaks!

3. Keep sure your elbows at a slightly open angle—90° or greater.

Keeping your elbows bent less than 90° can cause nerve compression, leading to sore wrists and arms. Adjust the height of your chair or your keyboard tray to achieve a comfortable position.

4. Keep your shoulders relaxed, and your elbows at your side.

You shouldn't have to raise your shoulders to get your hands to reach the keyboard—try raising your chair instead. Your forearms should be roughly parallel to the floor. If your chair has armrests, the armrests should comfortably support your elbows during rest breaks.

5. Don't use wrist rests or armrests while typing—only while resting.

If your workstation has wrist rests or armrests, be sure to use them only while taking breaks. Never use wrist rests or armrests while typing. A wrist rest should be used to rest the heel of your palm, not your wrist itself.

6. Stay centered on the lettered part of the keyboard.

Keyboards aren't symmetrical. Letter keys are on the left and the numeric keypad is on the right, but most people center themselves with the entire keyboard or keyboard tray—not the letters! This puts the keyboard a little too far to the left. If you use the letters most, it makes sense to align yourself with that section—the "B" key should be about in line with your belly button.

7. Consider using a voice recognition software program.

Voice recognition programs allow you to dictate to your computer and free yourself from the keyboard. There are a number of commercially available programs. Be aware, however, that this can lead to new problems such as voice loss!

8. Consider using keyboard shortcuts or macros to repeat common tasks.

Many of the commands available through menu choices can also be accomplished by using the keyboard. (For example, Ctrl-C can be used to copy text.). Some programs also allow you to automate common tasks (such as formatting a document or inserting your address) with scripts called macros. You can even buy software programs that allow you to easily record macros for any software and assign complex key sequences. These can significantly reduce the amount of typing you need to do.

Setup And Positioning

1. If you don't currently use an adjustable keyboard/mouse tray, consider attaching one to your surface.

This allows a much wider range of adjustment, and helps you maintain a proper ergonomic setup. Choose a system that is height adjustable, lets you tilt the keyboard away from you slightly for better posture (negative tilt), and allows you to use the mouse with your upper arms relaxed and as close to the body as possible.

2. Make sure the height of your keyboard allows you to keep an "open angle" with your arms.

In the proper position, the keyboard should be placed just above the level of your lap. This is lower than most people normally place their keyboard, but lets your arms tilt downward while using the keyboard, leaving your elbows at a comfortable "open" angle. (If you don't have an adjustable keyboard tray, you may need to accomplish this by adjusting your chair height).

3. If your keyboard is lower than the desk surface, tilt the back edge of the keyboard slightly down (known as "negative keyboard tilt").

Using a slightly negative keyboard tilt will help you keep your wrists in the proper (neutral) position. Try to avoid positive keyboard tilt (i.e., where the top row of keys is noticeably higher than the bottom row of keys). Also, make sure that if there are "legs" attached to the bottom front of your keyboard, they are left un-extended.

4. If you use a keyboard tray, make sure there's enough room for your mouse.

Your mouse should be close to your keyboard so that you don't have to reach far to grasp it.

5. If you have a broad chest, consider a "split" keyboard.

Split keyboards divide the keyboard into two halves, each of which points slightly outwards. The outward angle lets your wrists and forearms point inward without requiring your elbows to come in as far, better conforming to the contours of your body. Conversely, thinner people may find a traditional "straight" keyboard more comfortable.

Objective 3: Tips for Healthy Monitor Usage

1. Follow the 20/20/20 Rule

If you tend to work on your computer for prolonged periods of time, be sure to take a 20 second break every 20 minutes and look at least 20 feet away. This gives yours eyes a break and chance to adjust focus-a great way to avoid visual fatigue.

2. Keep a clean screen

Dust gathers easily on monitor screens. Be sure to periodically use a recommended solvent to remove any accumulated dust or fingerprints, ensuring a clean and visually consistent display.

There are a number of ailments that can come from using your mouse incorrectly, from sore wrists to aching shoulders. They may take years to develop, but once present, can be difficult to reverse.

Setup and Positioning

Choosing the right location for your computer monitor on the desk or workspace can be a difficult decision. Yet if not positioned correctly, your monitor can cause neck pain, shoulder pain, or even eye strain. The following guidelines can help determine the ideal ergonomic position for your monitor.

1. Sit arms' length away.

Your monitor should be about arm's length away when you're sitting back in your chair. (Sitting too close or too far from your screen can cause eyestrain). If you have a large monitor - 20" or larger - you should sit slightly further back.

2. Position the top of your screen level with your eyes.

The ideal viewing height is to have your eyes level with an imaginary line across the screen, about 2"-3" below the top of the monitor. This can be accomplished in one of two ways - either by either lowering your monitor or raising your chair. If your screen is too low, you'll find yourself tilting your head forward to view the monitor (a common cause of neck pain). If it's too high, you may have to tilt your head back, leading to neck and shoulder pain - and increasing the likelihood of glare from overhead lights (a common cause of headaches).

· Exception: If you wear bifocals or trifocals while using your computer, it may be appropriate to position your monitor a few inches lower than otherwise recommended to accommodate comfortable viewing through your lower lenses.

· Exception: If you use a large monitor (20" or larger), position your monitor so that the top of the viewing area is about 3" above eye level.

3. Balance the brightness of your monitor and its surroundings.

You should adjust your monitor so that its brightness is approximately equal to the area directly behind it. The goal is to eliminate any contrast between the brightness of the screen and the area behind it. (Make sure, of course, that your workplace is adequately lit!). Uneven brightness can cause headaches and vision issues (such as fatigue and squinting). You may need to adjust your screen brightness throughout the day if your workspace is lit by natural light.

4. Adjust your font size and color.

The size of your text should be about two or three times the size of the smallest text that you can read. Black text on a white background is usually the easiest to discern when word-processing.

5. Reduce glare.

If left uncorrected, glare will cause discomfort, eyestrain, and headaches. Try to reposition your monitor so that there's no glare on the screen (but avoid putting it in a position that's uncomfortable to view!). If you can't avoid the glare by readjusting your monitor positioning, consider a high-quality glass anti-glare screen.

6. Consider a swivel arm.

If you frequently interact with others, and placing your monitor in the recommended location would interfere with your interactions, consider purchasing a swivel arm. Swivel arms enable users to maintain proper monitor location while in use and easily swing their monitors out of the ways when not in use.

Objective 4: Tips for Healthy Mouse Use

1. Use your elbow-not your wrist-to move the mouse

Keeping your forearms in one place and using your wrists to "flick" the mouse can increase intracarpal pressure leading to wrist and finger pain.

2. Limit the amount you use your tracking device

Take breaks every 15-20 minutes and change your position frequently.

3. Use keyboard shortcuts

Many of the commands available through menu choices can also be accomplished by using the keyboard. (For example, Ctrl-C can be used to copy text.) These shortcuts can significantly reduce the amount you need to move your mouse

4. If you surf the web or edit long documents, consider a mouse with a scroll wheel

Scrolling with a wheel instead of the entire mouse helps reduce repetitive arm motions

5. Don't click too hard!

Just like typing on a keyboard, some people tend to use excessive force when clicking the mouse or trackball buttons. A light touch will do-and it will help save your hands and wrists!

6. Make sure you're holding your mouse correctly

Believe it or not, there's a right and a wrong way to hold your mouse. Here are a few tips to help:

  • Avoid letting your fingers "hover" above the mouse or trackball buttons. Some people are always "poised and ready" to click, holding their fingers over the button even when they're not using it. This causes unnecessary stress on your fingers. When you're not ready to click, you don't need your fingers raised-give them a rest by letting them relax or lay gently on the button.
  • Use a light grip. Just like typing too hard on a keyboard, holding your mouse too tightly can lead to pain.
  • Don't hold the mouse when you're not using it. Some people seem glued to their mouse. If there's a short period where you won't be using your mouse, you don't need to hold onto it.
  • Keep your wrists in a straight or "neutral" position. Avoid tilting (up and down) or angling (side to side) your wrists.

7. Try using your other hand to operate the mouse

Switching hands, or "load sharing," limits the amount that each hand has to work. It may seem strange, but it takes most people just a few days to get used to the change.

8. If you use a trackball, consider placing padding or a rest under your elbow

This can help reduce the work your shoulder performs in keeping your arm raised. Make sure you use different fingers to operate the trackball-using just your thumb can lead to discomfort!

Setup and Positioning

1. Place your mouse close to your keyboard and within easy reach.

Placing your mouse too far away can cause your shoulders muscles to tire from constantly supporting your outstretched arm, leading to neck and shoulder pain. Keeping it close to your keyboard means you won't have to overstretch when reaching for the mouse.

2. Keep your mouse close to your keyboard.

Placing your mouse on a desk if your keyboard is on a tray can cause you to overreach, and result in shoulder or neck pain. You should be able to use your mouse comfortably with your arms close to your side, and your elbows at a slightly "open" angle.

3. Consider a mouse tray to help keep your mouse near your keyboard.

Your mouse should be close to your keyboard, and both should be comfortably placed. If you are using a keyboard tray, the best position for your mouse is on an adjustable tray that slides over the numeric keypad of your keyboard, putting your mouse about 2 inches above your keyboard (known as a mouse bridge). If your keyboard tray has a tiltable mouse tray to the side, then try angling it down slightly to improve your wrist posture. Try to avoid using a mouse to the side of the keyboard on a flat, lowered tray, because this puts your hand in greater wrist extension.

4. Adjust your mouse/trackball's software controls.

Many people don't realize that the way their mouse functions can be controlled through software. You can adjust the speed at which your mouse moves, the time required between double-clicks, and the size of the cursor. If you're constantly having to backtrack because you shot past the "close window" button, try slowing your mouse down.

5. Consider using a different input device to reduce repetitive arm motions.

Trackballs decrease the distance your shoulder has to travel, which may help reduce movement-related pain. (However, they can also put more strain on the fingers and hands.) Some mouse designs work like a joystick and may help. You can also use a touch pad, a pen and tablet, or a foot-operated mouse. Try a variety of devices, and use the one that feels most comfortable.

6. Make sure you're using the right size-pointing device.

People often don't realize that mice may come in different sizes. Make sure that the mouse fits comfortable in your hand; if it's too large, you may want to find a smaller mouse. There are even adjustable-size mice.

Objective 5: Example of Medical Problem Associated with Ergonomics

1. Carpal Tunnel Syndrome

Today, roughly 3-5% of the computer users suffer from carpal tunnel syndrome. Since repetition of hand use is one factor causing carpal tunnel syndrome, the increase of computer use may be involved in this statistic.

What is carpal tunnel syndrome?
Carpal tunnel syndrome is a medical problem of the hands. The pinching of a large nerve, the medial nerve that travels under the palm, causes the problem. Normally, the nerve carries information about the sensation of touch from the hand to the brain, but when the nerve is pinched, the sensation of touch can be blocked.

Causes. The use of highly repetitive wrist movements appears to be connected with development of carpal tunnel syndrome, but medical conditions like diabetes, rheumatoid arthritis, thyroid disease, and pregnancy can be causes as well. In an office environment, carpal tunnel syndrome can be worsened by incorrect use of a computer keyboard.

Symptoms. The symptoms of carpal tunnel syndrome can include numbness, tingling, pain and weakness in the thumb, index, middle and ring fingers. Initially, the feelings may come and go, but the pain is often worse and night and can wake you up. The symptoms may worsen when you are doing forceful or repetitive work with your hands, like driving, gardening, cleaning, or using a computer. Symptoms, which would suggest the problem is not carpal tunnel syndrome, include pain in the forearm or shoulder, or worsening symptoms when reaching overhead (e.g., washing hair).

Prevention. The best prevention for individuals who may be at risk for carpal tunnel syndrome (data entry clerks, word processors, or computer programmers), is correct use of the keyboard and mouse.

2. RSI

What is RSI?

Repetitive Strain Injuries occur from repeated physical movements doing damage to tendons, nerves, muscles, and other soft body tissues. Occupations ranging from meatpackers to musicians have characteristic RSIs that can result from the typical tasks they perform.

Causes. The rise of computer use and flat, light-touch keyboards that permit high speed typing have resulted in an epidemic of injuries of the hands, arms, and shoulders. The usage of pointing devices like mice and trackballs are as much a cause. The thousands of repeated keystrokes and long periods of clutching and dragging with mice slowly accumulate damage to the body: another name for the condition is Cumulative Trauma Disorder. This can happen even more quickly as a result of typing technique and body positions that place unnecessary stress on the tendons and nerves in the hand, wrist, arms, and even the shoulders and neck. Lack of adequate rest and breaks and using excessive force almost guarantee trouble.


· Tightness, discomfort, stiffness, soreness or burning in the hands, wrists, fingers, forearms, or elbows

  • Tingling, coldness, or numbness in the hands
  • Clumsiness or loss of strength and coordination in the hands
  • Pain that wakes you up at night
  • Feeling a need to massage your hands, wrists, and arms
  • Pain in the upper back, shoulders, or neck associated with using the computer.

Prevention. Correct typing technique and posture, the right equipment setup, and good work habits are much more important for prevention than ergonomic gadgets like split keyboards or palm rests. Emerging research suggests that a monitor position lower and farther away may be better. Note that the chair and keyboard are set so that the thighs and forearms are level (or sloping slightly down away from the body), and that the wrists are straight and level - not bent far down or way back. If the table is too high to permit this, you may do better to put the keyboard in your lap. Also note that the typist is sitting straight, not slouching, and does not have to stretch forward to reach the keys or read the screen. Anything that creates awkward reaches or angles in the body will create problems. Please note that even a "perfect" posture may result in problems if it is held rigidly for long periods of time: relax, MOVE and shift positions frequently. This isn't just about your hands and arms, either: the use or misuse of your shoulders, back and neck may be even more important than what's happening down at your wrists.