Individual variation of postural control during bilateral- arm-movement in standing and relationship between initial posture and the variation

许多以前的研究表明，控制站立姿势的腿部和躯干的姿势肌肉的动作先于快速移动手臂的焦点肌肉。研究人员推断，姿势肌肉之前的动作会调节手臂快速运动引起的任何干扰的影响。在这些研究和我们的初步研究中，考虑了被认为对姿势调整产生影响的因素。在这些因素中，我们特别注意到了姿势运动，以及在手臂开始运动之前保持的姿势。我们得到了以下结果。1)所有受试者的足-腿和腿-躯干活动角的相关系数都很高(r=0.870)。关于姿势运动的个体差异，值得注意的是，髋关节的运动角度几乎是踝关节和膝关节的两倍。在许多受试者中，姿势肌的作用发生在局部肌肉作用之后，表现为髋关节屈曲模式。2)受试者根据安静站立时的站立姿势分为后、中、前3组。受试者在前后方向的不同CFP(足底压力中心)位置保持站立姿势，并以自己的步调开始双侧手臂的运动。仅在股二头肌中，按前、中、后三个组的顺序，在CFP较前的位置可清楚地观察到前三角肌的先行动作。3)在髋关节初始屈曲角度，竖脊肌和股二头肌在三角肌之前开始收缩。在伸展和0°时，有一半的受试者在髋关节向屈曲位移动时，在三角肌后开始收缩。4)网球击球时左侧髋关节运动角度与安静站立时双侧手臂运动角度具有较高的相关效率(r=0.785)。

Many previous studies have shown that the action onset in the postural muscles of the leg and trunk that control standing postures precedes that in the focal muscles that rapidly move the arm. Researchers have reasoned that the preceding actions of postural muscles modulate the effects of any disturbance caused by rapid arm movement. In these studies and our preliminary studies, factors thought to exert in influence upon postural adjustment were considered. In these factors, we noticed particularly the postural movement, and the posture maintained before the onset of arm movement. We get the following results. 1) The correlation coefficient in the movement angle between foot-leg and leg-trunk across all subjects was very high (r=0.870). With regard to individual variation in postural movement, it was noteworthy that the movement angle of the hip joint was almost twice as large as those of the ankle and knee joints. The action of postural muscles occurred after focal muscle action in many subjects showing the hip flexion pattern. 2) The subjects were divided into 3 groups depending on the standing position during quiet standing, namely backward, middle and forward. Subjects maintained standing postures at various CFP (center of foot pressure) positions in the auteroposterior direction, and the started bilateral arm movement at their own pace. In only the biceps femoris, the preceding action to the anterior deltoid was clearly observed at more forward CFP positions in the order of the forward, middle and backward groups. 3) At the initial hip joint angles of flexion, the erector spinae and biceps femoris begun to contract before the deltoid. At the extension and 0 °, they begun to contract after the deltoid in half of subjects when the hip joint moved toward the flexion position. 4) The movement angle of the hip joint in the left side during tennis stroke showed a high correlation efficiency (r=0.785) to that during bilateral arm movement in quiet standing.