The aim of this guide is to assist workers who spend a significant part of their workday at a seated workstation. Injuries often occur at seated workstations because workers mould themselves to the equipment provided rather than adjusting the equipment to suit their bodies.
There are many styles and makes of office chairs on the market. When selecting a chair, it is important that the following options are available. Seat height must be easily adjustable.
- A hydraulic mechanism is recommended.
- The back rest height should be adjustable.
- The back rest should be well padded to offer good back support.
- The base should be star shaped with five castor wheels for stability and manoeuvrability.
- Arm rests are not recommended – they get in the way of desk work.
Board room chairs, arm chairs, executive chairs and waiting room chairs are not designed for desk based or computer work – they are not recommended regardless of how comfortable they may seem.
Adjusting your chair
Adjust the seat height so that your feet rest firmly on the floor and that weight is taken through them.
- If in this position the desk is too high, the seat height should be raised and a foot rest should be used to support the feet.
- Ensure that your thighs are supported on the chair.
Allow a two finger space between the back of the knee and the front edge of the seat. This can be achieved by adjusting the back rest depth.
- Adjust the backrest so that your lumbar spine is well supported.
- Adjust the backrest height so that it is at the level of your waist.
- When this is complete the knees should be at a 90 degree angle.
Work Surface Height
Your desk work surface should be slightly above the height of the elbow when seated. This allows the elbows to be rested on the desk during writing. The keyboard should be approximately at elbow height so that the forearms are horizontal and the wrists are in a neutral position.
Adjusting Your Monitor Height & Distance
Ideally the top edge of the monitor screen should be at a horizontal eye level. This minimises the amount of neck flexion and extension required to view the screen image. The easiest way to raise the height of your monitor is by using phone books or custom-made platforms. Laptop monitors are positioned too low to be safely used for extended periods.
The distance of your monitor should be one full arms length when you are sitting in your usual position for keying. Having the monitor positioned too close or too far away can cause eye strain and increases your tendency to sit with poor neck posture.
Organising the Work Area
All materials should be within comfortable reach to minimise twisting and reaching. The most frequently used items should be within easiest reach.
Foot rests are required where a worker is unable to place their feet flat on the floor when sitting in a correctly adjusted chair. A correctly adjusted foot rest should allow the persons thighs to be at right angles with no pressure on the underside of the thighs.
The mouse should not place undue pressure on the wrist and forearm muscles.
- Avoid stretching the arm forward.
- Keep arm by side of the body with the forearm supported by the work surface.
- Move the keyboard away if necessary.
- Avoid constant use without rest breaks.
- If possible, it may be useful to learn to use the mouse with either hand.
Rest & Exercises
Variation of tasks and rest breaks are very important. Frequent short breaks are recommended when performing desk-based work to avoid strain.
Exercises and stretches should be performed regularly. It is important to stretch slowly and gently and never stretch to the point of pain. Some exercises you may like to try are shown. If you experience pain, or already have an injury, consult your physiotherapist for advice.