It is generally recommended that your keyboard and mouse be at approximately elbow height with your heels comfortably on the floor. Ergotron has height recommendations for these parameters but the best way to determine the heights required is to take measurements of the person who will be using the desk.
If your desk is higher than this, footrests and keyboard trays are often recommended to improve ergonomics. Buying tips and pros and cons for these interventions are outlined below.
Footrests provide foot support when tasks require your chair to be raised so that your heels are no longer comfortably on the ground but there are some things to watch out for:
- With your chair higher, it will be more difficult to roll your chair to other parts of your desk. As a result, you may introduce new risk factors like reaching for items instead of moving your chair or grabbing your desk to pull yourself to other parts of your desk.
- It can make it more difficult to get on and off your chair.
- It will raise your centre of gravity, increasing the risk of your chair tipping over while rolling, especially if there is any unevenness on the floor around your desk.
- If you need to work at different places at your desk, you may need more than one footrest.
- Footrests are generally not height adjustable or have limited ranges of height adjustment. As a result, you may not be able to get your chair to exactly the height that you need. Some footrests claim to be height adjustable but may only be tilt adjustable.
Before investing in a footrest:
- Check to see if your chair goes high enough to improve upper extremity posture at your desk. A new higher gas lift for your chair or a new chair may be required.
- To determine how high your footrest should be, make note of your elbow height when your heels are on the ground. The height difference between that height and the top of your desk is approximately how high your footrest should be.
- Footrest width: note how far apart your feet are when you sit with your heels on the floor. Your footrest should be at least that wide. Having your feet a comfortable distance apart helps to maintain a balanced seated posture and provides an opportunity to vary your posture while sitting. Consider placing 2 footrests side by side if you can’t find one wide enough.
- The legs of your chair can bump into the footrest making it difficult to position properly. Look for a design that is open at the front.
Setting your seat height with your footrest:
- Move your chair away from your desk.
- Raise your chair to its highest setting.
- Sit on your chair with your footrest beneath your feet.
- Lower your chair until you feel comfortable.
- If you are most comfortable with your chair at its highest setting, you may need a chair that goes higher.
- Stand up and move your chair and footrest to where you sit at your desk.
- Sit down and assess your upper extremity posture.
- If you feel like you are too high, move the footrest farther away and change the tilt, so you can lower your chair a bit.
- With a keyboard tray, your keyboard and mouse position will be addressed but pay attention to anything that remains on your desk (e.g. monitor height, paper-based tasks). Paper-based tasks such as writing can be comfortably performed on a surface approximately 2 inches above elbow height.
- Keyboard trays require sitting farther away from your desk, which may increase reaches to items on your desk. (Note: some furniture systems have a cut-out for the tray which addresses this concern.)
- Compare how far the mechanism and adjustment knobs extend below the keyboard tray. Banging legs against the mechanism is a common complaint.
- Check the range of adjustment to ensure that its height range is sufficient for your needs.
- At a minimum, the tray should be wide enough to accommodate your keyboard and provide space to move your mouse. A tray that is wider than this minimum will be useful if you place the mouse to the right of your keyboard for the following reason. A tray that only meets the minimum width requirement, will require the left edge of the keyboard to align with the left edge of the tray, so you will sit closer to the left edge of the tray. This can bring your right knee into contact with the mechanism in the middle of the tray as opposed to having each knee equidistant from the mechanism.
- When considering the width of the tray, keep in mind that some keyboards may be larger than the keyboard you are currently using.
- Some keyboard trays are available in widths to accommodate more tasks. These trays often have dual arms which can make it difficult to swivel in your chair without hitting them.
- There are pros and cons to 2 part systems with separate surfaces for the mouse and keyboard. One of the pros is that you typically can sit with the mechanism centred between your legs.
- Some keyboard trays do not go into forward tilt to prevent wrist bending for low keyboard positions. However, in some situations higher positions and the ability to forward tilt is useful (e.g. if you look at the keyboard when typing, if you wish to recline while typing)