An Ergonomic Design and Evaluation of a Chair with a Flexible Seat Pan for the Maintenance of Correct Sitting Posture

This study evaluates the ergonomic benefits of a novel chair featuring a four-segment flexible seat pan designed to support correct sitting posture. Motion capture and electromyography tools are used to quantitatively assess the impact of different chair designs on pelvic and lumbar angles and muscle usage through two ergonomic experiments (short- and long-term). In the short-term experiment (30 participants), the proposed chair demonstrated significant improvements in maintaining the spine’s S-shape, with hip and lumbar angle enhancements of up to 15.3° compared to a conventional chair. The long-term experiment (20 participants) revealed that the proposed chair led to a more favourable muscle fatigue profile during prolonged sitting, with a 47% decrease at lower frequencies (0 to 20 Hz) and a 34% increase at higher frequencies (60 to 80 Hz) compared to the conventional chair, indicating reduced muscle fatigue. These results suggest that the proposed chair can significantly improve posture and reduce fatigue in settings that require prolonged sitting.