Differences In Regional And Global Lumbar Angle During Slumped Sitting And Upright Sitting Among Global Three Subgroups

OBJECTIVE: The purpose of this study was to investigate differences in regional lumbar lordosis (RLL) and global lumbar lordosis (GLL) angle during slumped sitting and upright sitting among three global subgroups.METHODS: A total of 48 young asymptomatic volunteers stood in a comfortable posture, sat upright, and sat in a slumped position for 5 seconds, with inertial measurement units attached to the T10, L3, and S2 vertebrae. According to standing measurement, the participants were categorized into flat-back (GLL < 20 degrees), normal lordosis (20 degrees <= GLL < 30 degrees), and hyper-lordosis (30 degrees <= GLL < 40 degrees) groups.RESULTS: Both the GLL and RLL in the flat-back group were reduced lumbar lordosis in the upright sitting posture and increased lumbar kyphosis in the slumped sitting postures compared to the other groups (p < 0.05), but the range of motion during the transition from upright sitting to slumped sitting was lower than that of the normal and hyper-lordosis groups (p < 0.05). GLL in standing was a moderate correlation with GLL and RLL during upright sitting (p < 0.05). However, there was a strong correlation between GLL and RLL kinematics during upright and slumped sitting (p < 0.05).CONCLUSIONS: Flat-back posture is a potential source of low back pain during both upright and slumped sitting compared to the normal and hyper-lordosis groups. Posture measurements in a standing and sitting position conducted to assess lordosis should consider the relationship between GLL and RLL.