Standard Sitting Posture for Office Chairs

The standard sitting posture for office chairs should follow the following key points to ensure health and work efficiency:

1. Adjust the seat height
   The seat height should allow the thighs to be parallel to the ground, with the knees bent at a 90-degree angle. When sitting, the buttocks should fully contact the seat surface, avoiding leaning forward or backward. If the seat height is fixed, a footrest can be used to adjust it, ensuring that the feet are flat on the ground. For low stools, the standard should be that the feet are naturally perpendicular to the ground, the thighs are perpendicular to the calves, and there is no pressure on the knees; if the feet cannot touch the ground when leaning against the chair, it indicates that the chair height is not suitable and needs to be replaced or adjusted.

2. Strengthen lumbar support
   The lumbar spine should maintain its natural forward convex curve. A lumbar support can be added to the backrest or a memory foam cushion can be used. The support should be placed between the third and fifth lumbar vertebrae, with a thickness suitable for maintaining a slight forward convexity of the waist. For those who work at a desk for long periods, it is recommended to choose an ergonomic chair and avoid using backless stools or overly soft sofas to reduce lumbar spine pressure and prevent lumbar muscle strain.

3. Keep feet flat on the ground
   The feet should fully contact the ground, shoulder-width apart, avoiding crossing the legs or sitting with legs crossed. The ankles should be kept at a 90-degree angle to prevent obstruction of blood circulation in the lower limbs. If the feet are suspended due to insufficient height, a footrest should be used for support; women wearing high heels are advised to keep flat shoes in the office for changing to maintain the natural arch of the feet and reduce foot fatigue.

4. Adjust the screen to eye level
   The top of the computer screen should be level with or slightly lower (10-15 cm) than the eyes, with a distance of 50-70 cm maintained. Laptop users are advised to use a stand to elevate the screen and connect an external keyboard; the center line of the screen should align with the bridge of the nose to avoid long-term looking down or up, which can cause cervical spine retroflexion. For those using multiple screens, the main screen should be placed directly in front, with auxiliary screens at a 30-degree angle to reduce neck twisting.

5. Optimize desk-chair matching and activity frequency
   After sitting firmly, fix the elbow joints and slowly raise the arms to a natural下垂 position. The height at this point is the suitable desk height, ensuring that the forearms and wrists remain in a straight line to prevent mouse elbow and mouse wrist. The best distance between the chest and the edge of the desk is a fist's width. In addition, it is necessary to get up and move for 1-2 minutes every 30-40 minutes, performing micro-movements such as cervical spine backward bending and scapular contraction to relieve muscle tension.

Correct sitting posture requires a combination of equipment adjustment and active rest. Long-term adherence can significantly reduce the risk of occupational diseases such as cervical spine, lumbar spine, and eye fatigue.