Adjust the seat tilt allowing the seat to tilt forwards slightly. Ensure you are comfortable, you may prefer the seat pan in a horizontal position. If the chair is fitted with a seat slide ensure it is in the correct position. There should be approximately a two-three finger width clearance between the front of the seat and the back of the knees.
Your knees should be bent at a comfortable angle and greater than 90° flexion. If this places an uncomfortable strain on leg muscles, or if the feet are not flat on the floor, then a footrest must be used.
The height of the footrest should be adjustable to allow knees to be bent at 90° and is usually the distance the feet are off the floor after adjusting the seat height. A footrest should:
- have a non-slip surface large enough for both feet to rest comfortably (approximately 300 x 300mm),
- have an adjustable slope (10-20 degrees) to allow a comfortable ankle position when feet are resting on it, and
- be stable enough so it does not slide or move.
Adjust the backrest so that it supports the lower back when you are sitting upright. The lumbar support should be positioned in the natural curve of the spine directly behind the belly button or at waist level.
Chairs can be purchased with or without armrests. If armrests are selected they must be height adjustable.