Many of us rely heavily on computers to help us perform our work - for some, dedicated computer work is necessary, while others multi-task throughout the day. No two people are the same, and ergonomics strives to fit the task to the person doing it.
The office ergonomics guide is intended to guide you in a self-assessment of the ergonomic design of your computer workstation. These helpful tips can show you how to identify and correct ergonomic problems to prevent repetitive strain injury, eyestrain, fatigue and discomfort. If you have any further questions or need an assessment, please contact Andrew Scheifele ext. 36359 in the Safety Office.
Along with the information contained in the following pages, the Safety Office has office ergonomics information available in an attractive poster format. These posters are produced in general office or student computer lab versions and are available from Sheila Hurley in the Safety Office ext. 33587. Also, for preventive office exercise tips, see the workstation exercises.
To get started, move through the components of your workstation - evaluate and adjust each one in order, according to the guidelines.
An ergonomic chair will not function as designed unless you know how to operate the adjustable features correctly. To adjust your task chair, follow the steps:
Sitting in the chair, raise or lower the seat so that your feet rest comfortably on the floor. Your knees should be slightly lower than your hips.
Sit as far back in the chair as possible, and adjust the backrest height or lumbar support so that it fits into the curve in your lower back.
If you have a seat slider, adjust the seat pan depth so that a closed fist fits between your knee and the edge of the seat.
Adjust the backrest angle to achieve a torso-to-thigh angle of 93-113 degrees (have someone else look at you from the side).
Adjust the seat pan tilt angle to a comfortable position.
Adjust the armrest so that it is at your elbow height. If the armrests swivel, place the armrests in line with your forearm when you are using the mouse.
Once you have adjusted the rest of your workstation, if your feet do not reach the floor, use a footrest.
Remember to adjust your chair throughout the day to help relieve muscle tension in specific muscle groups.
Check to ensure that the ergonomic task chair has the appropriate ergonomic features before purchasing one.
Keyboard and mouse
There are numerous keyboard and mouse configurations and models available, however it is important to correctly position these tools to prevent overuse injuries.
To properly position your keyboard and mouse, follow these steps:
- Sit close to the keyboard and mouse so that your upper arms hang in a relaxed position.
- Center yourself so that you are aligned with both the keyboard and mouse, depending on what is most frequently used. Position the mouse as close as possible to the keyboard to avoid rotating the shoulder.
- Adjust the height of the keyboard platform (or chair if there is not an adjustable platform), so that your shoulders are relaxed and elbow angle is 90 degrees or slightly greater.
- Adjust the angle of the keyboard platform slightly downward in a negative tilt, if able. This will help to keep your wrists straight.
- Do not put the mouse where you must stretch to the desk or out to the side of a keyboard to reach it.
- Your wrist should be straight while mousing, not angled toward your thumb or little finger.
Some other important tips to limit overuse and awkward postures:
- Move the mouse from the elbow, rather than from the wrist down.
- Alternate mousing between left and right hands. Mouse buttons can be reconfigured to allow either hand to be used.
- Rest your finger lightly on the mouse button, do not hold it hovering above the mouse.
- Do not grip the mouse tightly - hold it gently and glide it over the surface.
- Choose a mouse that fits your hand, and that can be used with either hand.
- Use shortcut keys whenever possible to limit mouse use.
- If you are correctly positioned, a wrist rest should not be necessary. However, when a neutral wrist posture cannot be achieved or to reduce contact with hard surfaces, a wrist rest may be helpful. Do not plant your wrists on the pad while keying or mousing. Make sure the wrist rest is made of a soft gel or foam to minimize pressure on the underside of the wrist.
- Key with gentle, quick keystrokes. Do not pounds on keys as this increases the force exerted.
- You can position the mouse over the numeric keypad with an articulating mouse platform or mouse "bridge".
- When mousing is a constant requirement (e.g. CAD applications), the forearm should be supported on a surface or with an adjustable armrest to reduce static loading of the arm.
- Alternative keyboards and mousing devices are available to accommodate for specific needs.
Proper monitor positioning is important in avoiding vision and neck problems. Follow these steps:
- The monitor should be positioned so that your natural gaze falls about one-third down the length of the screen.
- The distance should be about arm's length (45 to 60 cm). Font size, specific applications and personal visual acuity and sensitivity will also determine the correct distance, however placing the monitor too far away can cause the user to lean forward and can lead to eyestrain.
- Bifocal users should lower the monitor so that text can be viewed through the proper prescription. Increasing the distance away from you also increases the field of vision available without moving the head. Tilting the screen upward slightly can also help.
- The monitor should be directly in front you, aligned with the area of the keyboard that you use most.
- Adjust contrast and brightness to your personal needs to reduce eyestrain.
- Look away from your screen periodically - focus on a distant object to exercise eye muscles.
Reference documents, especially when used frequently, should not be placed flat on the work surface. Instead, use a document holder. Traditional holders position the document adjacent to the monitor, however there are models that allow the user to place several items directly between your keyboard and monitor, avoiding awkward neck postures and maximizing productivity.
The telephone needs special attention if you use it often. Cradling the phone between the shoulder and ear causing awkward neck and shoulder postures, and can lead to injury if used for prolonged periods or frequently throughout the day.
If you use the telephone frequently, a headset should be used to allow for hands-free operation. This will eliminate cradling of the phone between shoulder and ear while writing, handling documents or using the computer.
In a general office environment, the CSA recommended lighting level for computer work is 500 lux. These lighting levels can be adjusted for personal preference, and paper work may be augmented by task lighting.
Glare is the main lighting concern when working with computers. To help minimize glare:
- Position monitors parallel to overhead lights and perpendicular to the windows
- Ensure wall colour is neutral (not too bright)
- Remove or cover shiny surfaces and objects
- Use blinds or curtains to minimize window glare
- Install diffusers on overhead fluorescent lights
- Adjust the angle of the monitor, so that the screen is vertical
- Use incandescent task lights over source documents, but direct them away from monitor
One of the best ways to prevent injury, discomfort and fatigue is to take an ergo break - a pause or change in activity that allows muscles, joints and tissues that have been working to recover and rest. Muscles that remain in a static posture will fatigue, circulation will decrease, and you will notice discomfort. This may mean taking a short pause in activity to focus on a different task, rest your eyes, and most of all, change position. Prolonged sitting is one of the major risk factors for low back pain, so give your back a break and stand, walk and stretch. It may also mean switching to another task that requires the use of different muscle groups and postures.
An ergonomic task chair is the basis for a comfortable, productive workstation. Ergonomic means that the chair has the necessary adjustable functions and standard qualities that make it suitable for the majority of the population. To assist users in identifying a good ergonomic chair, some of the important features to look for are summarized below.
Ergonomic chair features
|Seat height||Adjustability is a must - feet should rest comfortably on the floor without pressure on the back of the thighs. The angle between the thigh and torso should not be less than 90°.|
|Seat depth||The seat should have a waterfall edge and be the right depth. Too short, and pressure will result on the back of the thighs, too long and the seat edge will press into the back of the knee. A seat slider is a good option to provide adjustable depth.|
|Seat pan angle||Should allow the user to keep the feet flat on floor and should move proportionally to backrest angle.|
|Lumbar support||The backrest curve should follow the natural curve of the spine, so when purchasing, always look for an adjustable lumbar support.|
|Backrest height||The backrest needs to adequately support the back. Mid-back chairs are most popular since they allow for upper torso movement , while high-back chairs support the shoulder blades as well. Low-back chairs (<45 cm tall) are not recommended.|
|Backrest angle||A great adjustable feature to allow for the recommended 93°-113° torso-to-thigh angle, plus provide a changing posture throughout the day.|
|Armrests||Should be height adjustable between 19-24 cm and should naturally support the arms at the elbow and forearm with a padded surface, without the user leaning or elevating the shoulder. They should not interfere with computer work or positioning of the chair, so should be set back from the front edge of the chair 15 cm.|
It can be overwhelming to try to choose an appropriate chair that fits both your physical needs, the job that you do, and your budget. In order to assist with this process, below is a list of popular chair manufacturers and models used at UWaterloo. The chairs detailed on this page are not University of Waterloo standards and do not represent all available models, however are popular choices appropriate for general office workstations. Many local reps will provide a demo of the chair you are interested in, to ensure that the model you purchase is the right fit.
ErgoIndustrial lab stool
Contact procurement & contract services to purchase ergonomic furniture or equipment.
If you have a concern or special need, contact
Andrew Scheifele in the Safety Office.
Laptops are a popular and often necessary addition to the traditional office - for those who need portability, they are a time-saving way to bring the office with you. However, the attributes that make laptops so portable also create ergonomic hazards that users should be aware of.
The main concerns with laptop use is the fact that the keyboard and the screen are contained in one unit. This goes against the ergonomic principle that the keyboard should be located at elbow height, and the screen at eye level. Although new technology has improved laptop screen viewing, they are still not optimal, especially for full-time users.
Setting up a laptop "workstation"
Using a laptop in an awkward posture for over 1-2 hours can cause temporary discomfort, and prolonged or repeated use can cause musculoskeletal injury. It is important to be aware of when "a few minutes" is up.
For short-term use, for example while travelling or checking in while out of the office, the following quick tips can help to improve comfort:
- Sit in a comfortable chair that supports your back, preferably one that reclines slightly.
- If the laptop is on a table, try to position it so that your wrists and elbows are in a neutral position. Avoid high counters or tables if you are sitting - consider standing at a suitable counter if needed.
- Tilt the screen away from you, to place it in line with your natural line of sight - it is usually necessary to tilt the neck slightly. Try to work in an area that limits glare on the screen.
For long-term use, the following steps should be followed to avoid discomfort or injury:
- At a minimum, place the laptop on a work surface that allows your wrists, elbows and shoulders to remain in a relaxed and neutral posture.
- Tilt the screen to your line of sight. Better yet, plug in an external monitor or keyboard and mouse to separate the two components.
- Position all components correctly using a monitor riser, laptop holder or keyboard platform, according to the office ergonomics guide.
Laptop docking stations are another way to accommodate and improve ergonomics. They serve to position the laptop at an angle that elevates the screen, but keeps the keyboard at a reasonable angle. When using a platform, it is important to be able to rest the elbows and forearms on a work surface.
Transporting your laptop
Carrying a laptop, plus accessories, peripherals and documents can lead to handling of heavy loads. It is important to properly store and transport your laptop to avoid heavy and/or frequent lifting and carrying.
Transport your laptop in a carrying case - a shoulder bag is suitable for loads under 10 lb, however for heavier materials, a backpack type will distribute weight evenly over the shoulders while leaving your hands free. Depending on the additional items you require, consider using a rolling case with extending handle for heavier loads or when transporting over long distances.