Dolan P, Mannion A F, Adams M A
Department of Anatomy, University of Bristol, U.K.
J Biomech. 1994 Aug;27(8):1077-85. doi: 10.1016/0021-9290(94)90224-0.
We examined the possibility that passive tissues can help the erector spinae to generate large extensor moments during lifting. One hundred and forty-nine healthy men and women participated in the study. Subjects pulled upwards with steadily increasing force on a floor-mounted load cell, while EMG activity was recorded from electrodes overlying the erector spinae at L3 and T10. Extensor moment was calculated from the load cell data, and was plotted against the full-wave rectified and averaged EMG signal. The relationship was linear with an intercept on the extensor moment axis (I) which indicated the flexion moment resisted by 'passive' (electrically silent) tissues. The dependence of I on lumbar flexion angle was studied by repeating the isometric pulls between 6 and 12 times, with the subject positioned in varying amounts of flexion, as measured by the '3-Space Isotrak'. Subjects then lifted weights of up to 20 kg from the floor, using 'stoop', 'squat' and 'freestyle' techniques, while lumbar flexion and EMG activity were recorded at 28 Hz. The isometric pulls showed that, on average, I increased from 25 Nm in lordotic postures to 120 Nm (for men) and 77 Nm (for women), in full flexion. During the lifts, peak extensor moment was generated with the lumbar spine flexed by 78-97% of the range between erect standing and full flexion.(ABSTRACT TRUNCATED AT 250 WORDS)
我们研究了在举重过程中被动组织是否有助于竖脊肌产生较大伸展力矩的可能性。149名健康男性和女性参与了这项研究。受试者以逐渐增加的力向上拉动安装在地面的测力传感器，同时记录L3和T10水平竖脊肌上方电极的肌电图活动。根据测力传感器数据计算伸展力矩，并将其与全波整流和平均肌电图信号作图。该关系呈线性，在伸展力矩轴（I）上有一个截距，它表示由“被动”（电静息）组织抵抗的屈曲力矩。通过使用“3-Space Isotrak”测量，让受试者处于不同程度的屈曲状态，等长拉动重复6至12次，研究I对腰椎屈曲角度的依赖性。然后，受试者使用“弯腰”“深蹲”和“自由式”技术从地面提起重达20千克的重物，同时以28赫兹的频率记录腰椎屈曲和肌电图活动。等长拉动表明，平均而言，I从脊柱前凸姿势下的25牛米增加到完全屈曲时男性的120牛米和女性的77牛米。在举重过程中，腰椎屈曲达到直立站立和完全屈曲之间范围的78%至97%时产生最大伸展力矩。（摘要截短于250字）
