Precautions When Sitting on an Office Chair

When sitting on an office chair, it is important to pay attention to the chair's fit, design factors, proper use of adjustment functions, and maintaining correct sitting posture to avoid lumbar spine injuries and accidental chair tilting.

I. Strictly Self-Check the Chair's Fit Most 'ergonomic chairs' purchased by companies may pose a risk of misaligned support. If you need to actively straighten your back to fit against the chair back or if the armrest height does not match the desk height, causing you to type with raised shoulders, it indicates that the chair is depleting your spinal health reserves. You can perform a self-check with three actions:

1. Lumbar Support Fit: After sitting down and relaxing naturally, if there is a significant gap between your waist and the chair back, it indicates that the position or shape of the lumbar support does not match and cannot effectively support the third to fifth lumbar vertebrae.
2. Seat Depth Rationality: When your feet are flat on the ground, there should be a fist-sized distance between the back of your knees and the front edge of the seat cushion. If the seat depth is too long, it can compress the blood vessels and nerves in the back of your thighs, leading to impaired blood circulation.
3. Armrest Height Fit: When your arms hang naturally, your elbows should be bent at a 90-degree angle and your shoulders relaxed. If the armrests are too high, requiring you to raise your shoulders, or too low, causing your arms to hang in the air, it can lead to shoulder and neck muscle fatigue.

II. Check the Chair's Design Factors

1. Tilting Mechanism Risk: A chair with an improperly locked tilting function may suddenly tilt backward due to gravity when you sit down, causing you to lose balance.
2. Material and Structural Stability: If the seat material is too soft (e.g., low-density foam) or the base structure is unstable (e.g., insufficient load-bearing capacity of the five-star base), it can cause the chair to tilt backward due to uneven weight distribution, especially for individuals with a heavier build.

III. Operate the Adjustment Functions Correctly

1. Tilting Tension Adjustment: If the resistance is set too low, the chair may tilt backward with slight movements when you sit down; if the resistance is too high, you will need to exert force to lean back, increasing the burden on your lumbar spine. It is recommended to adjust the resistance to a moderate level that allows for slow backward tilting based on your body weight.
2. Locking Mechanism Check: Before use, ensure that the locking device (e.g., knob or toggle) is fully secured. If the locking fails, the chair may move suddenly during use, posing a risk of falling.

IV. Implement Correct Sitting Posture Points

1. Height Adjustment: The seat height should keep your thighs parallel to the ground and your knees bent at a 90-degree angle, avoiding foot suspension or excessively high knees.
2. Lumbar Spine Support: Maintain the natural forward convex curve of your lumbar spine. You can add a lumbar support or use a memory foam cushion on the chair back, ensuring that the support is precisely placed on the third to fifth lumbar vertebrae.
3. Foot Posture: Keep your feet fully in contact with the ground and shoulder-width apart, with your ankles at a 90-degree angle, avoiding crossed legs or standing on tiptoe.
4. Arm Placement: When hanging naturally, your arms should be able to easily touch the desk, avoiding suspension due to a low desk or shoulder raising due to a high desk. If necessary, use an adjustable-height desk for coordination.