Ergonomics is the science of fitting the job to the worker doing that job. The goal of ergonomics is to reduce a worker’s exposure to MSD risk factors, which we will talk about later. Ergonomics may include engineering or designing the layout of a workstation, in our case the computer workstation, so that the worker’s exposure to MSD risk factors is reduced. The way or sequence in which a job is done may also be changed to help reduce MSD risk factors. Administrative controls include rotating employees through a job with higher MSD risk factors so that employees are only exposed for a short period each day. For example, a job with heavy data processing might be shared by four employees that perform other duties when not doing the data process.
A proper understanding of ergonomics is critical. “ Matches” is the key word. It means that ergonomics is process, not a product. “ Job” encompasses a few components: (1) the workstation's physical shape and size, (2) the design of the tools, equipment and machinery to be used, (3) the environmental conditions Job content: tasks -- their variety and sequence, work- and rest-breaks Worker: skills, work practices, work habits, worker’s active input To achieve a “perfect”, or at the very least, acceptable match, all these components must be considered.
Ergonomics includes things like proper seating, workstation set up, proper keying and mousing positions and placing yourself in neutral and non stressful positions.
Place your computer monitor directly in front of and facing you. Keep the monitor at or slightly below eye level. Do not put your monitor off to the side so that you have to turn your head to look at it. Your monitor should be about arm’s length away to prevent eye strain. Sit back in your chair as you would when working and reach toward the monitor—you should be able to touch it with your fingertips. Keep the text size large so that you do not strain your eyes to read. After being seated properly, the monitor should be placed such that your eyes are aligned at the top of the screen. Tilt the monitor back just slightly to help prevent glare. You should not have to tilt your head up or bend your neck down to see it. Place any documents that you are reading as close to the monitor as possible and at a similar angle as the monitor. Use a document holder. This will prevent unnecessary turning of your head to read or review documents related to your computer activity.
A comfortable and ergonomic chair is critical when working at a computer workstation for extended periods each day. First we will focus on the seat surface. The seat surface should be properly padded and comfortable, even after sitting for 30 to 60 minutes. The width of the seat should be at least an inch wider than your hips and thighs. To determine the appropriate length of the seat surface, sit with your back against the lumbar support. In this position, the front edge of seat should be about an inch or two from the back of your knee. Also, the front edge should be contoured so that you are not subjecting the back of your legs to contact stress of the front of the seat. The chair height must be adjustable so that your feet can rest on the floor or on a footrest. Some seat surfaces can also be tilted to help you maintain a balanced posture. You may prefer a seat that is tilted slightly forward so that you can easily reach the keyboard and supplies on the workstation; or, you may want the seat surface tilted back to help you stay seated against the back support.
The backrest of a chair is very important because you need adequate back support when working at a computer workstation for extended periods. You should be able to adjust the angle of the backrest relative to the seat surface so that you can lean back, forward, or sit straight up, depending on what is comfortable for you. The backrest must also have an adjustable lumbar support that goes up and down. Armrests must be broad, cushioned, and comfortable. However, you should not lean on the arms because when working a mouse or keyboard, you want to keep your wrist straight and work the mouse with movement from your elbows. The armrest should provide support for your shoulders, elbows, and wrists so that they can be maintained in the neutral position when working. The armrests should also be adjustable independently in both height and side to side so that they will fit the user of the chair properly.
Your knees should be comfortably bent at about 90 degrees. The angle does not have to be exact, as long as you are comfortable. Your thighs should be approximately parallel to the floor. Adjust your chair so that your feet can be flat, your thighs parallel to the floor, and your knees bent about 90 degrees. Also, make sure the chair has a curved front edge so that it does not put pressure on the back of your thighs. Remove any obstructions to your legs and feet so that you can maintain a comfortable working position. Your feet should be resting comfortably flat on the floor or a footrest.
These five Musculoskeletal Stress Disorder (MSD) risk factors are the major contributors to MSD-related injuries and illness. Prolonged exposure to one or more of these risk factors in your job puts you at risk of an MSD. Repetition might include daily and lengthy use of a keyboard or mouse. Force might include constant lifting, pushing, or pulling. Awkward postures might including extending arms to type or sitting forward with hunched shoulders. Contact stress might include soft tissue damage by contact with a hard surface such as leaning against a counter or continual use of a stapler or hole punch.
Carpal Tunnel Syndrome: Compression of the median nerve, which provides sense of touch for fingers, where it passes through the wrist and into the hand. Usually the result of repetitive motion such as typing. Tendinitis: Tendon inflammation that occurs when a muscle/tendon is repeatedly overused. Tenosynovitis: Inflammation or injury to the synovial sheath surrounding the tendon. Usually the result of excessive motion. Trigger Finger: Tendon becomes locked and attempts to move the finger cause snapping or jerking motions.
While using the keyboard, keep your elbows close to your body. Avoid reaching for the keyboard or allowing your elbows to extend away from your body. Adjust the height of your keyboard so that your wrists are in a neutral position and in line with your forearms. Remember, your elbows should be bent about 90 degrees. Your hands and wrists must be in line with your forearms. Hands that are bent up or down or turned in or out will put stress on your nerves and muscles. Do not rest your wrists on a hard surface, sharp edge or wrist rest when typing. This puts pressure on your carpal tunnel. You should only use the wrist rest during a typing pause.
To achieve the neutral typing position discussed in the last slide, the keyboard tray must be adjustable. Remember, you have already positioned your chair and monitor; now it is time to adjust your keyboard to fit your size and posture. The keyboard must be placed in a keyboard tray that is height-adjustable so that the user can maintain the neutral position. Placing the keyboard at a “negative tilt,” such that the back of the keyboard is lower than the front, will help you maintain a neutral hand/wrist position. The keyboard tray holder should accommodate both the keyboard and mouse on the same surface at the same height to allow neutral keying and mousing positions. Finally, make sure the keystroke pressure is comfortable for the user. Today's keyboards typically have comfortable keystroke pressure.
Most people consider the keyboard to be the main contributor to computer workstation MSD injuries. However, the mouse, when used heavily and improperly, will also contribute to computer MSD injuries. Control the mouse movement from your elbow. Controlling the mouse with wrist movements will put a strain your nerves and other soft tissue in your wrist. Keep your wrist straight and neutral and move or turn at your elbow slightly to make mouse movements. Position your mouse properly. You should not have to reach or extend your arm or body to use the mouse. DO NOT GRIP the mouse, float the mouse.
All of these exercises and stretches can be done while sitting in a chair. Exercises help strengthen muscles and allow overworked areas to stretch. Practice the following “workouts.” Hand— Finger extensions . Make a fist, then extend and spread your fingers. Wrist— Bend hands up and down . Hold arms out in front of your body and bend hands up and down Wrist— Backwards stretch . Palms together with fingers pointed upward and elbows pointed out, bring your hands down toward your waist until you feel the stretch. Shoulder— Shrug and roll your shoulders . Shrug your shoulder and then roll your shoulders forward and back. Shoulder— Shoulder blade pinch . With elbows out, move your arms back to bring your shoulder blades together. Shoulder— Overhead reach . Reach your arms overhead and stretch, bend from side to side.
Ergonomics For Pc Users
بسم الله الرّحمن الرّحيم How we can prevent MSDs?
Using Ergonomics’ principles. <ul><li>Science of fitting the job to the worker </li></ul><ul><li>Reduces exposure to MSD risk factors </li></ul><ul><li>Involves engineering and administrative controls </li></ul>Ergonomics
What is Ergonomics? <ul><li>Ergonomics is the discipline that matches the job to the worker </li></ul><ul><li>and product to the user. </li></ul>
percentage Facilities 90 Internet 83 E-mail 76 Word processing 17 Games 14 programming
The distribution of the pain perception reported by the respondents
Study in India <ul><li>stress in 35%. </li></ul><ul><li>visual problems in 76%, </li></ul><ul><li>musculoskeletal problems in 77.5% </li></ul>
Who’s At Risk? <ul><ul><li>Nearly everyone, </li></ul></ul><ul><ul><li>but women report more incidents of discomfort </li></ul></ul><ul><ul><li>Low motivation </li></ul></ul><ul><ul><li>Poor workstation design </li></ul></ul>
Computer Monitor <ul><li>Directly in front of you </li></ul><ul><li>Arm’s length away </li></ul><ul><li>Proper height </li></ul><ul><li>Documents placed close to monitor </li></ul>
<ul><li>It is observed that occurrence of visual problem is related more to number of hours spent gazing at the screen than number of years </li></ul>
<ul><li>Prevention </li></ul><ul><ul><li>Task rotation </li></ul></ul><ul><ul><li>Get a professional eye examination </li></ul></ul><ul><ul><li>Control the lights & the monitor </li></ul></ul><ul><ul><ul><li>Enough light on documents </li></ul></ul></ul><ul><ul><ul><li>Eliminate glare </li></ul></ul></ul><ul><ul><ul><ul><li>Rearrange the workstation </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Anti-glare screen </li></ul></ul></ul></ul>Eye Strain
Appropriate Breaks <ul><li>Breaks are not always rest periods </li></ul><ul><li>Balance work activities with worker “biorhythms” </li></ul><ul><li>Change position and tasks at least every two hours </li></ul><ul><li>Tasks must use different muscle groups and vary requirements for posture, pinch and grip </li></ul>
Temperature <ul><li>At 18.8 degrees Celsius workers typed 54 percent of the time and with a 25 percent error rate. When the temperature was raised 25 degrees Celsius the workers were typing 100 percent of the time and with a 10 percent error rate. </li></ul>
Low back pain When these curves become either exaggerated or flattened, the spine increasingly depends on muscles, ligaments and soft tissue to maintain erect.
Ergonomic Chair: Back and Armrest <ul><li>Backrest </li></ul><ul><li>Angle adjustable </li></ul><ul><li>Adjustable lumbar support </li></ul><ul><li>Armrest </li></ul><ul><li>Broad and cushioned </li></ul><ul><li>Supports shoulders, elbows and wrists </li></ul><ul><li>Adjustable height and side-to-side </li></ul>
Computer Workstation: Legs and Feet <ul><li>Knees bent about 90 degrees </li></ul><ul><li>Thighs parallel to the floor </li></ul><ul><li>Chair at comfortable height </li></ul><ul><li>Remove any ob structions to your legs and feet </li></ul>
Task Rotation & Breaks <ul><li>Some companies have actually installed software that “shuts down” the system for regular breaks </li></ul><ul><li>Other companies have organized or signaled breaks </li></ul><ul><ul><li>These can be aggravating, as they interrupt a task in progress </li></ul></ul>
Neutral Keyboard Position <ul><li>Elbows close to the body </li></ul><ul><li>Wrists flat and in line with the forearms </li></ul><ul><li>Hands not angled up/down or turned in/out </li></ul><ul><li>No wrist rests when typing </li></ul>
Adjustable Keyboard <ul><li>Height adjustable </li></ul><ul><li>In a tilting keyboard tray </li></ul><ul><li>Detachable from the computer monitor </li></ul><ul><li>Keystroke pressure comfortable for the user </li></ul>
Using a Mouse <ul><li>Control mouse movement from your elbow </li></ul><ul><li>Wrist straight and neutral </li></ul><ul><li>Locate mouse close to you with no reach </li></ul><ul><li>Float mouse – Do Not Grip the mouse </li></ul>