Protruding Part of Office Chair

The design and impact of the protruding parts of office chairs vary depending on their type and design purpose, and can be divided into the following three categories:

1. Spring protrusions in old chairs
Due to prolonged use, the internal springs of old office chairs may deform due to metal fatigue or structural aging, resulting in local protrusions on the seat or backrest. This protrusion usually manifests as a single-point hard pressure, directly contacting the perineal area (i.e., the base of the pelvis) when seated. Its direct impact is not squeezing the abdomen or constricting the waist, but continuous single-point pressure can cause concentrated stress at the base of the pelvis. Long-term use may alter bladder nerve sensitivity, leading to frequent urination or abnormal urination reflexes after prolonged sitting. Such issues are commonly seen in chairs used for more than 5 years and require replacement of the springs or the entire chair for resolution.

2. Sacral support protrusions in ergonomic chairs
Modern ergonomic chairs often feature short, vertical protrusions on the backrest, positioned to correspond with the sacrum (the junction of the lumbar spine and tailbone). The design principle is to maintain the natural S-shaped curve of the spine and disperse lumbar pressure through a horizontally forward-pushing support force. These protrusions must meet two standards: the protrusion height should not exceed 3 centimeters, and the surface should be covered with high-density foam or breathable mesh fabric to reduce the sensation of hard contact. When used correctly, they can reduce the risk of lumbar muscle strain caused by prolonged sitting, but if the protrusion is misaligned (e.g., too high and pressing against the lumbar spine) or the material is too hard, it may cause sacrococcygeal pain.

3. Front-high, back-low, middle-protruding design in mesh office chairs
In response to the elastic properties of mesh materials, some chairs adopt a curved design with a slightly higher front, a protruding middle, and a sunken back. When a user sits down, the mesh sags under gravity, and the middle protrusion counteracts the sagging, resulting in a seat surface that ultimately conforms to the buttocks and thighs. This design enhances breathability and reduces pressure on the buttocks but has weight adaptability limitations: users weighing over 90 kilograms may experience excessive sagging of the mesh, leading to compression of blood vessels and nerves beneath the thighs and causing numbness. It is recommended that such users choose models with thicker mesh or additional independent seat cushions.

Summary: The design of protrusions on office chairs must balance support and comfort. Spring protrusions in old chairs are a fault phenomenon, while sacral support protrusions in ergonomic chairs represent scientific design. The curved protrusions in mesh chairs require selection based on body weight. Regularly checking the structural integrity of the chair and choosing a model that fits one's body type can effectively reduce health risks associated with prolonged sitting.