Office Ergonomics
Many people don't realize that a poorly designed computer workstation and/or bad work habits can result in serious health problems. Common symptoms associated with poor design or habits include discomfort in the back, neck and shoulders, hands and wrists, as well as headaches and eyestrain. If you experience any of these symptoms while working, contact the UEOHC for medical help.
Fortunately, the solution can be quite simple. Proper workstation setup and work practices can eliminate discomfort and even prevent it from occurring in the first place! Simple adjustments to office equipment can work wonders, making work more comfortable and more productive.
I want to learn more about...
- Common Office Equipment
- Lighting
- Rest Breaks
- Exercises
- Keyboard Shortcuts
Chairs
- What to look for in a chair
- Why not to use an exercise ball for a chair
- Chair reviews
- Setting up my chair
- Rationale behind these recommendations
Starting from the bottom and moving upwards:
Base: The chair should have at least 5 castors at the base to ensure stability. Why?
Seat: The seat should be able to adjust until your thighs are parallel to the ground. Shorter/taller users may need different height cylinders. If you are unable to adjust your chair heigh properly, contact the chair manufacturer for a replacement cylinder. Why?- The seat pan depth should be adjustable to provide a fist-width to three-finger gap between the back of the calf and the front edge of the seat pan. Why?
- The seat pan should be able to tilt backwards and forwards. Why?
- The seat pan should have a waterfall (rounded) front edge. Why?
Backrest: The backrest height should be adjustable so the lumbar support can be fitted into the low back. Why?
- The backrest should be able to recline independently of the seat pan and be set at a fixed reclined angle. Why?
Armrests: Firstly, armrests are optional. Even with the range of adjustments found in many of today's armrests, there are some places where armrests will interfere with work.
- The armrests should be adjustable in height. Why?
- They should be rounded on the edges. Why?
- Optional: most armrests are spaced too widely apart for the user to use them comfortably. Armrests that are width-adjustable to slide over the seat pan until they are right under the elbow or armrests that pivot inwards (the kind that can pivot almost all the way around are preferable) are much more functional than simple height adjustable armrests. Why?
Why not to use an exercise ball for a chair
Considering using an exercise ball as your office chair? Think again. What may seem like a good idea to you or others is actually not recommended. Read the following articles for further information:
- Replacing Office Chairs with Exercise Balls
By Heather Ritz - Opinion: Balls as Office Chairs a Bad Idea
Start out adjusting a chair from the ground up. Start with the height and move up from there. While adjusting the chair, worry first about getting the chair adjusted to fit you. Afterwards, look at things like the height of the desk, keyboard, etc. Too often, people adjust a chair too high so they can reach the keyboard rather than properly adjusting the chair and adding a keyboard tray to move the keyboard to the correct height.
Seat Height: Start by adjusting the height until your thighs are parallel to the floor. Stand in front of the chair and adjust the height until the top of the seat pan is at the height of the bottom of your kneecap. Then, sit in the chair and make small height adjustments until your thighs are parallel to the ground. Sit in this position for a while before making any further changes in seat height. When you have become accustomed to this height, adjust the chair height up/down 1-3 inches until you find a location that is comfortable for you while seated (don't worry about that keyboard height yet!).
Seat Depth: Adjust the seat pan until you have about three fingers to a fist's width of room between the back of your calf and the front edge of the chair when your back is touching the backrest. If the seat pan is not adjustable and the pan is too deep, add padding to the backrest (a towel over the backrest of the chair or a backrest cushion) to shift you forward in the seat while maintaining contact with the backrest. If the seat pan is too shallow, start looking for a new chair.
Seat Angle: There are three basic postures. The standard posture calls for a level seat pan so it is not necessary to adjust the tilt for this posture. Likewise, the reclined posture can have the seat flat as well. However, some people prefer to have a very slight backward tilt on the seat pan to hel keep them in the seat. In the forward tilt posture, the seat pan is tilted forward 5-10°. Start by raising the overall height of the chair a few inches, and then tilt the seat pan forward.
Backrest Height: The lumbar curve on the backrest should fit into the small of your back. Start by raising the chair back as high as possible and then move the backrest downward in small steps until it feels most comfortable. If the chair doesn't have enough lumbar support consider adding a lumbar pad to the chair. Make sure the extra pad doesn't make the seat pan too short!
Backrest Angle: In the standard posture and forward tilt postures, the backrest should be straight up. If it feels as though the chair is pushing you forward, adjust the backrest back until you feel upright. In the reclined posture, the backrest should be reclined slightly. When seated, the angle between the thighs and back should be more than 90°.
Armrests: As previously mentioned, armrests can sometimes interfere with work. If they prevent you from pullingup to your desk or reaching for the mouse, either lower them until they are out of the way and don't use them, or have them removed. Armrests are "rests" not "supports". Typing with the arms constantly on the armrests is not recomended.
Armrest Height: Sit in the chair with your arm bent 90° and raise the armrest until it is directly under your elbow. Repeat the process with the other arm and then check that the armrests are the same height.
Armrest width/pivot: Some armrests pivot or slide inwards, allowing you to change the angle and width of the armrests. Adjust the armrest inwards until it is directly under your elbow while your upper arm/shoulder is relaxed. You should not have to reach your elbows outward to reach the armrests. If the armrests pivot, pivot them slightly inwards so they are underneath your forearms when you reach inwards to the keyboard.
Rationale behind these recommendations
Five castor base: Chairs with five castors are more stable than four castor chairs. Four castor chairs are easier to tip over.
Seat Height: Adjusting the chair too high places more pressure than necessary on the backs of the legs, reducing circulation. If the chair is too low, a smaller portion of the legs is in contact with the chair and the pressure on that area is correspondingly greater.
Seat Depth: If the seat pan is too shallow, all the pressure from sitting is placed on a small part of the thighs, which may lead to discomfort. If the seat pan is too deep, it will either be difficult to use the backrest or the front of the seat will put pressure on the back of the nerves and tendons at the backs of the knees.
Seat Tilt: Changing your posture thoughout the day is positive because when you change postures, the loads of sitting shift to different parts of the body, allowing your body to recover from extended static postures.
Rounded Edges: Sharp corners, even when they're made of padding, increase the pressure on the backs of the thighs. A rounded front edge distributes the pressure over a larger area.
Backrest Height: The backrest should mirror the shape of your back to provide support. The weight of the upper body is supported by the spinal vertebrae at the bottom of the lumbar curve (curve at the small of your back). These same vertebrae are the most common origins of back pain. Using the backrest to support the lumbar curve relieves some of the pressure on the frequently injured vertebrae.
Backrest Recline: It is acceptable to sit upright or recline slightly in your chair as long as the backrest is designed for reclined seating. A slightly reclined posture opens up the angle between the hips and trunk, which decreases the stress placed on the low back.
Armrest Height: If the armrests are too high, you might have to shrug your shoulders in order to use them, which could fatigue your shoulders and back. Conversely, if they are too low, then you might end up leaning on one armrest.
Rounded Edges: Sharp corners, even when they're made of padding, increase the pressure on the arms. A rounded edge distributes the pressure over a larger area.
Armrest Width: If the armrests are spaced too far apart, they will not be directly under the elbows. In order to use the armrests, users have to hold their arms slightly away from the body. This reach can fatigue the shoulder muscles.
Footrests
What to look for in a footrestUse footrests as a last resort. Footrests are a way to shift postures or provide support for the feet if the chair cannot be lowered. Unfortunately, using a footrest when the chair is too high provides only one place for the feet to rest. The seated person only has the footrest and the castors under the chair as places for their feet and this limits the postures they can shift through throughout the day. The preferred solution is to add a shorter cylinder to the chair (see the chairs section), and lower the desk height until the desk surface is approximately 1 inch above seated elbow height.
Height: A footrest should be height adjustable. Adjust the footrest until the thighs are parallel to the floor +/- 1-3 inches.
Rocking: When using a footrest, be sure to shift postures frequently. Some footrests have a rocking feature that allows the user to rock the footrest, increasing circulation and helping avoid static postures. The rocking action on all-plastic footrests tends to wear out quickly, so look for durable models.
Keyboard Trays
What to look for in a keyboard tray
The purpose of a keyboard tray is to change the height and angle of the keyboard without interfering with how the user uses the keyboard and mouse. Therefore, the tray should be easy to adjust, have enough room for the keyboard and mouse and not prevent the user from typing with the keyboard at forearm length from the body.
Height: The tray should be height adjustable until the mouse and keyboard are at or slightly below elbow height. Avoid keyboard trays that require unscrewing a knob every time the height is adjusted. Knob-adjusted trays discourage users from making small adjustments in height and the knob, often located under the tray, may hit the user's knee and prevent them from sitting close enough to the keyboard and mouse to use them properly. Many newer trays have lever-less mechanisms, which allow users to adjust tray height by lifting the front edge and either pulling up on or pushing down on the back edge.
Angle: The tray should be angle adjustable to align the forearm with the keyboard. Often this will require a "negative tilt" where the front of the keyboard is higher than the back. For some users, it may be necessary to adjust the angle of the mouse surface as well to prevent the mouse from rolling off the tray.
Mouse: The tray should have space for the mouse beside the keyboard at about the same height.
Wrist Rest: If the tray comes with a wrist rest, it should be soft foam or gel and be removable. Not all keyboards will fit on a standard keyboard tray with the wrist rest attached.
Height: Sit upright in the chair and bend your elbow 90°. Hold your open palm down and raise the keyboard tray until the keyboard is just under your fingers. Keep the keyboard at this height or slightly lower as desired. Reach to the side and check to be sure the mouse is just under your hand as well. Some keyboard trays have mouse attachments that attach to the side and below the keyboard. If this places the mouse too low, put additional mousepads under your mouse until it is at approximately the same height as the mouse.
Angle: Hold your hand, palm open, over the keyboard. Tilt the tray to align the angle of the keyboard with the angle of the forearm. If the keyboard is below elbow height, this will require a negative slope where the spacebar edge of the keyboard is higher than the back edge. In most cases, the keyboard will be either flat or tilted at a negative slope. Do not use the feet on the back of your keyboard or tilt the tray at a positive slope unless you are seated in a reclined position. Even when reclined, start with the keyboard flat before trying a positive tilt.
Mouse: Place the mouse beside the keyboard tray and at about the same height. On trays where there is room for the keyboard and mouse on the same tray, place the mouse beside the keyboard. On trays where there is a mouse attachment attached underneath the tray, check the mouse height in the same way as the keyboard height. Additional mousepads are a good way to raise the mouse. Some trays have a mouse attachement above the keyboard. These attachements slide or pivot to cover the numeric keypad on the right hand side of the keyboard and reduce side reaching to use the mouse. Keep these trays pivoted over the numeric keypagd when not using the keypad.
Keyboards
What to look for in a keyboard
There are many keyboard designs available. This page will cover the two most common keyboard designs. The standard flat keyboard and the split keyboard. For a more in-depth review of keyboard designs, see Ergonomics of Alternative Keyboards and the National Institute for Occupational Safety and Health brochure on alternative keyboards.
Standard Flat Keyboard: This is the standard rectangular keyboard with a numeric keypad on the right hand side.
Split Keyboards: These keyboards are split in the middle (between the g and h keys) and the halves are moved at an angle to each other. The theory is that angling the sides will keep the wrists straight. These keyboards are often tented upwards slightly in the middle.
Wrist Rests: Many keyboards have built-in or detachable wrist rests. These rests are usually hard plastic and, where possible, should be removed. If the wrist rest is not removable, keep in mind that these are wrist "rests," not wrist "supports". They should be used only during pauses while keying.
Location: The number pad creates an optical illusion when aligning the keyboard and monitor, particularly with standard keyboards. The monitor is usually lined up with the center of the entire keyboard (apporximately the ';' key). The user, however, sits lined up with the center of the letters portion of the keyboard (approximately the 'g' and 'h' keys). This causes the user to either twist slightly to face the monitor or sit centered to the monitor and reach to the side to use the keyboard. When seated at the workstation, align the "gh" keys with the bellybutton and also check that the "gh" keys are centered with respect to the monitor.
