Lavender S A, Chen I H, Trafimow J, Andersson G B
Department of Orthopedic Surgery, Rush-Presbyterian-St. Luke's Medical Center, Chicago, Illinois, USA.
Spine (Phila Pa 1976). 1995 Jan 15;20(2):184-90; discussion 190-1. doi: 10.1097/00007632-199501150-00009.
Surface electromyographic activities were measured in 15 subjects as they maintained a static laterally bent trunk posture and resisted sagittally symmetric and asymmetric moments applied to their torsos. The moment magnitudes were 20 and 40 Nm and had transverse plane directional components in 30 degrees increments surrounding the subjects' torsos.
To quantify the myoelectric responses from eight trunk muscles as asymmetric loads were applied to the laterally bent torso.
Asymmetric material handling frequently results in lateral bending of the torso. Each of these factors have been linked via epidemiologic investigations to the incidence of low back disorders. Little information is available that describes the response of the trunk muscles when the trunk is bent to the side.
Subjects stood in a reference frame and adjusted their trunk posture to marks on a video display that indicated when a 20 degrees lateral bend to the right had been achieved. Moments were applied to the torso by connecting weights via cables and pulleys to a chest harness. Electromyographic activities were recorded bilaterally from the erector spinae, latissimus dorsi rectus abdominis, and external oblique muscles.
The electromyographic data indicated that the muscles showed the greatest activity when they were in opposition to the applied sagittal and frontal plane moments. The left external oblique showed the greatest response and was sensitive to the widest range of moment direction conditions. All of the muscles, except for the left latissimus dorsi, at times contributed antagonistic moments in the sagittal plane or the frontal plane, or in both planes. These data were compared with previously obtained data from an upright neutral posture.
Statistical analyses indicated that the responses of both external obliques and the left erector spinae to the moment direction conditions were significantly different between the laterally bent and neutral postures.
对15名受试者在保持静态侧屈躯干姿势并抵抗施加于其躯干的矢状面对称和不对称力矩时的表面肌电图活动进行了测量。力矩大小为20和40牛米，且在受试者躯干周围以30度增量具有横向平面方向分量。
量化在向侧屈躯干施加不对称负荷时八块躯干肌肉的肌电反应。
不对称的物料搬运经常导致躯干侧屈。通过流行病学调查，这些因素中的每一个都与下背部疾病的发生率有关。关于躯干向一侧弯曲时躯干肌肉反应的信息很少。
受试者站在一个参考框架中，根据视频显示器上的标记调整其躯干姿势，这些标记指示何时达到了向右侧20度的侧屈。通过将重物经电缆和滑轮连接到胸部背带向躯干施加力矩。从双侧竖脊肌、背阔肌、腹直肌和腹外斜肌记录肌电图活动。
肌电图数据表明，当肌肉与施加的矢状面和额状面力矩相反时，它们表现出最大的活动。左腹外斜肌表现出最大的反应，并且对最广泛的力矩方向条件敏感。除了左背阔肌外，所有肌肉有时在矢状面或额状面或两个平面中都产生拮抗力矩。这些数据与先前从直立中立姿势获得的数据进行了比较。
统计分析表明，在侧屈姿势和中立姿势之间，腹外斜肌和左竖脊肌对力矩方向条件的反应存在显著差异。
