Office Chair Backrest Too Thick

An excessively thick backrest on an office chair can have various negative impacts, including altering the natural curvature of the spine, affecting body-seat fit, and restricting body movement.

Firstly, a thick backrest can alter the natural curvature of the human spine. In a normal sitting posture, the lumbar spine has a certain degree of lordosis, which is part of the spine's 'S' shape. However, when the backrest is too thick, it increases the lordosis angle of the lumbar spine, causing excessive posterior convexity of the waist. This alteration disrupts the normal structure of the spine and, over time, can easily lead to muscle fatigue in the waist, resulting in issues such as lower back pain. This is because the waist muscles need to exert continuous effort to maintain this unnatural posture, increasing the burden and fatigue on the muscles.

Secondly, a thick backrest can affect the fit between the body and the seat. An appropriate backrest should closely conform to the body's curves, providing uniform support. However, an excessively thick backrest changes the support points between the body and the seat, preventing the body from fully conforming to the seat. This can make a person feel unstable while sitting, leading to unconscious adjustments in posture to maintain balance. Such frequent posture adjustments not only increase the physical burden but may also cause pain or discomfort in other areas.

Additionally, a thick backrest may restrict body rotation and posture adjustments on the seat. During office work, people often need to rotate their bodies or adjust their postures to meet different work requirements. However, an excessively thick backrest restricts these natural movements, making it difficult to maintain a comfortable sitting posture. This not only affects work efficiency but may also have long-term negative effects on physical health.

It is worth noting that there is no unified standard for the thickness of chair backrests. However, according to ergonomic standards, the recommended thickness for ordinary backrest chairs is between 15 and 20 millimeters. This range can better balance support and comfort, providing sufficient support without imposing unnecessary burdens on the body.