상체 굽힘과 비틀림에 따른 근육 동원형태에 관한 연구

Abstract

Hyper-flexion and twisting postures in lifting tasks have been identified as risk factors of low back pain. The current study investigated the recruitment patterns of eight trunk muscles in isometric exertion tasks during lifting in the asymmetric postures. One healthy male college student was recruited and performed isometric exertions under conditions of four trunk flexion angles (0°, 15°, 30° and 45°) and two asymmetric angles (0°, 30°, (clockwise)) while EMG signals from eight trunk muscles were monitored during 10 seconds. The results showed that the flexion angle and twisting angle significantly influenced the muscular activity of erector spinae, internal oblique, external oblique and latissimus dorsi. Activation level of the erector spinae increased continuously when trunk extension angle increased from 0° to 45°. However, the activation level of the internal oblique and external oblique decreased continuously when trunk extension angle increased from 0° to 45°. Also, left internal oblique, external oblique and latissimus dorsi activities were higher in the right muscles during the twisting posture (clockwise). This study indicated that erector spinae activities increased considerably with increasing the trunk extension and twisting angle and internal oblique, external oblique activities increased considerably with increasing the twisting angle. Therefore, exposure to the extreme flexion and twisting motion during lifting tasks could be a risk factor of the low back pain.