인체공학적 좌석이 척추와 골반 자세에 미치는 영향에 대한 생체역학적 비교연구: 원추형 진자 스툴과 반강성 유연 등받이 의자

Abstract

The most common health problem caused by long-term sitting lifestyle and degenerative changes due to aging was changes in spinal pelvic posture. Sitting posture was a more complex phenomenon because it follows a change in posture. The most common working environment occurs in working with your body tilted back from a chair with a backrest. While sitting down and working, the movement of the seat plate was restricted which result in stiff lumbar spine and pelvic muscles to become stiff that eventually causes fatigue, pain and pathological posture changes. The aim of this study was to analyze the biomechanical changes and effects by evaluating and measuring the changes in spino-pelvic posture including muscle tension in sitting posture according to the type of seat used. Two different type of ergonomic seats, such as conical pendulum stool (CPS) and semirigid flexible backrest chair (SFBC), were used in a total of 17 participants. Among two types of sitting, seat-buttock contact pressure and radiographic changes of coronal trunk imbalance distance (Gravitiy line/Hip axis distance), pelvic and shoulder height differences on the seats were measured and statistically analyzed using partied t-test. The seat-buttock contact pressure reduced from 51.13 ± 32.77 Ω and 59.13 ± 39.62 Ω on initial seated to 38.57 ± 25.61 Ω and 49.37 ± 29.22 Ω on 1hr seated on CPS and SFBC, respectively (p=0.486, p=0.332). Radiographically, changes in pelvic height differed statistically significantly between two sitting types of CPS versus SFBC (average of 2.12 + 2.61 mm versus 4.29 + 4.04 mm, respectively with one hour seating, p=0.008). Improvement in shoulder height difference was statistically significant (average of 8.27 + 6.28 mm to 5.37 + 6.06 mm using CPS from initial to one hour sitting, p=0.038). CPS seating showed better biomechanical effect in reducing the imbalance between pelvic height and shoulder height through the stimulating dynamic control of spinal stability and equilibrium by activation of the upper and lower back core muscles than static ergonomic seat.