What are the considerations for ergonomic office chairs for the human body?

A good office chair should be designed according to ergonomics, allowing people to work in the most comfortable and relaxed way, reducing the burden on muscles and joints, and evenly distributing pressure to achieve health goals.

The vertical height of a chair or sofa seat from the ground: excluding cushions, the height of an office chair is 410-450mm. Sitting on it with both feet dangling without touching the ground can easily compress the soft tissues in the knee pit and cause numbness in the legs. If the seat is too low, it can increase pressure on the ischial area, cause fatigue in the buttock muscles, and increase the load on the back muscles, which can be difficult to handle.

Seat depth of ergonomic chairs:

If you sit too deep, your backrest will not be supported, your knee pit will be compressed, and if the seat is too shallow, the soft tissues in the front of your thighs will be compressed, causing numbness in the thighs after sitting for a long time.

Most chairs have a depth of 400-500mm, and for chairs and sofas used for resting, the depth of a reclining chair can be greater, usually 490-570mm. A chair or sofa seat can be slightly curved, which is beneficial for muscle relaxation and movement. In order to provide proper support for the ischial joints, the seat depth and height are usually inversely proportional.

Seat width of ergonomic chairs:

To provide sufficient support for the human buttocks and allow people to adjust their posture at any time, there should be a certain amount of rotation space. The width of a general chair is greater than 390mm, the width of an armchair is greater than 470mm, and the width of an armchair seat is usually 510-550mm. If many people sit on a chair or sofa, the width of the seat should be based on the width of their shoulders and clothing plus an allowance of 50-100mm.

Backrest of ergonomic chairs:

In order to provide sufficient support for the trunk while not obstructing the arms on the backrest, the backrest should be greater than 280mm.

Armrests and armrest height of ergonomic chairs:

(1) Reduce fatigue in the shoulders, back, and hips, and rest the muscles of the upper body.

(2) The height of the armrests from the surface and the vertical height of the valve seat surface should be 210-250mm. If the armrests are too high, the arms cannot naturally hang down, and if they are too low, the elbows will naturally rest on the armrests, causing shoulder fatigue.

Adding soft cushions can increase comfort. If the seat cushion is too soft, the compressive strength and body support will decrease, and instability will increase. When sitting, discomfort in the abdominal pressure can occur, making it inconvenient to sit up, and causing fatigue. The different pressure distribution and body sensation between the backrest and the seat support require a slightly hard package to support the waist. The appropriate sinking height of the seat cushion is 75mm.

Because people's body types vary, when choosing an ergonomic chair, it is important to choose one that can be adjusted so that everyone can adjust to their most comfortable position. Otherwise, larger people may find the chair uncomfortable, and smaller people may find it too big, which can lead to physical problems caused by prolonged sitting.