Lumbar Posture Effects on Trunk Muscle EMG in Holding Tasks

靜態持物作業下腰椎姿勢對軀幹肌群活動之影響

陳一郎(Y. L. Chen) ； 李永輝(Y. H. Lee)

《人因工程學刊》 1卷1期 (1999/03) Pp. 39-48

摘要

本研究主要探討不同靜態持物情況下，腰椎姿勢對於四塊腹背肌群（腹直肌(RA)、腹斜肌(EO)、背闊肌(LD)與背棘肌(ES)）等肌電訊號(EMG)與腰椎曲度(LSA)的影響。自變項包括兩種腰椎姿勢（屈背、弓背）、四種軀幹前彎角度(0°、30°、6°、90°)、三種膝關節屈曲角度(0°、135°、90°)及三種持物重量水準(0、10、20kg)，實驗進行中同步蒐集EMG與LSA資料。實驗結果發現，當軀幹前彎180°時，兩種腰椎姿勢下的LSA差異極小（平均2.4°），而膝關節屈曲效果也不明顯，顯示LSA在此軀幹姿勢下受到體及膝關節的限制。不論身體的姿勢如何，屈背時的ES訊號均顯著大於弓背時，而其它的肌群活動訊號則幾乎維持不變。相較於弓背時的拉伸，在屈背時產生較大的ES肌群活動可提供脊椎良好的保護，對於抬舉作業而言，是較有利的腰椎姿勢策略。

關鍵字

肌電訊號EMG ； 腰椎姿勢 ； 腰薦椎角度LSA

並列摘要

The purpose of this study was to examine the effects of lumbar posture on both the electromyographic activities (EMG) of four trunk muscle groups (rectus abdominis (RA), external oblique (EO), latissimus dorsi (LD), and erector spinae (ES)) and the lumbar curvature (lumbosacral angle, LSA) under various load holding postures. EMG and LSA were recorded simultaneously as the subject held a load (0, 10, or 20 kg) with trunk flexion (0°, 30°, 60°, or 90° to the vertical), knees bending (straight, 135°, or 90°), and the lumbar spine in a posture of lordosis or kyphosis. Difference in LSA between the lumbar postures nearly disappeared (with a mean of 2.4°) when the trunk was flexed to 90°, The effect of the knee bent on LSA was also disappeared. This implied that the change of LSA in this posture was constrained by a flexed hip and a bend knee. EMCI results indicated that the activation of ES were the largest among all in lordosis than in kyphosis independent of trunk and knee angles. While the recruitment patterns of other muscle groups remain unchanged by this posture effect. A larger ES muscle activity in lordosis may provide a better protection for the lumbar spine than that in a kyphotic posture where ES was relatively stretched. This supported that lifting with a lumbar lordosis strategy is advantageous.

並列關鍵字

Electromyogram EMG ； lumbar posture ； lumbosacral angle LSA