Vertical Backrest of Office Chairs
A vertical backrest on office chairs may pose health risks, particularly for men aged 42 and above. The specific impacts are as follows:
1. Increased risk of lumbar muscle strain
The human spine has a natural physiological curvature when viewed from the side, with the lumbar spine forming a forward-convex arc. An office chair with a vertical backrest moves the support surface away from the concave area of the lumbar spine, leaving the forward-convex part of the lumbar spine unsupported. In this case, the back muscles need to continuously exert force to maintain trunk stability, resulting in an isometric contraction state. This continuous contraction compresses the microvessels within the muscles, slowing down local blood flow, reducing oxygen supply, and preventing the timely removal of metabolic waste (such as lactic acid). Long-term accumulation can lead to muscle fatigue, spasms, and eventually lumbar muscle strain. Studies indicate that men aged 42 and above have reduced muscle elasticity and repair capacity, making them less tolerant of such poor support and significantly increasing their risk of developing the condition.
2. Altered breathing patterns and nervous tension
When a vertical backrest fails to provide effective support for the waist, the ribcage is passively lifted to maintain balance, limiting the movement space of the diaphragm. As a result, the body is forced to adopt short, rapid thoracic breathing instead of deep abdominal breathing. This shallow breathing pattern reduces the efficiency of gas exchange in the lungs, leading to an increase in carbon dioxide concentration in the blood, which in turn stimulates sympathetic nerve excitation. Excessive activation of the sympathetic nerves further tightens the muscles, creating a vicious cycle of "shallow breathing - nervous tension - muscle stiffness" that may lead to chronic fatigue syndrome over the long term.
3. Core principles of ergonomic design
Although some office chairs with vertical backrests (such as the Gedeli G22) improve comfort through zoned backrests and flexible lumbar support technologies, the gold standard in ergonomic design remains a friendly angle of 110ยฐ-120ยฐ between the backrest and the waist. This angle allows the spine to naturally adhere to the backrest, distributing the weight of the upper body through the elastic support and inclination of the backrest, reducing pressure on the lumbar spine. For example, when the backrest is tilted by 15ยฐ, the pressure on the lumbar spine can be reduced by approximately 30%, significantly lowering the risk of lumbar muscle strain.
Recommendation: When choosing an office chair, prioritize testing whether the backrest angle meets ergonomic standards and avoid long-term use of chairs with vertical backrests. If a vertical backrest chair must be used, try to provide lumbar support by adding a lumbar cushion or adjusting the seat height.
