Kaminski T R
Department of Biobehavioral Sciences, Teachers College, Columbia University, Box 199, 525 West 120th Street, New York, NY 10027, USA.
Gait Posture. 2007 Jul;26(2):256-62. doi: 10.1016/j.gaitpost.2006.09.006.
When performing whole body reaching movements, all four limbs participate in the task. We hypothesized that the synergies that characterize upper and lower extremity movement are flexible and become coupled into one functional unit to transport the body towards the target. To test this hypothesis, subjects reached to three targets, one within and two beyond arm's length. In addition, subjects reached at two speeds and either stopped at the target or returned to the original start position. To assess the coupling during the various whole body reaches, a principal component analysis was performed on the displacements of the five primary joints used to accomplish the task (ankle, knee, hip, shoulder and elbow). Analysis of the loadings from the principal component analysis indicated that the first component represented the reaching element of the task, while the second and third components represented the postural element. When reaching within arm's length the variance explained by the joint coupling was distributed between the first three principal components. However, as reach distance increased, the distribution shifted with most of the variance being explained by the first principal component. Neither movement velocity nor final joint configuration affected the coupling between the joints. Analysis of center of mass indicated that it shifted progressively forward as reached distance increased. We conclude that as target distance increased, the reach and postural synergies became coupled resulting in the arms, legs and trunk working together as one functional unit to move the whole body forward.
在进行全身伸展运动时，四肢都参与到任务中。我们假设，表征上肢和下肢运动的协同作用是灵活的，并会耦合为一个功能单元，将身体朝着目标移动。为了验证这一假设，受试者向三个目标伸展，一个在手臂可及范围内，另外两个超出手臂长度。此外，受试者以两种速度伸展，并且在目标处停下或返回初始起始位置。为了评估各种全身伸展过程中的耦合情况，对用于完成任务的五个主要关节（脚踝、膝盖、髋部、肩膀和肘部）的位移进行了主成分分析。主成分分析的载荷分析表明，第一个成分代表任务的伸展要素，而第二个和第三个成分代表姿势要素。当在手臂可及范围内伸展时，关节耦合所解释的方差分布在前三个主成分之间。然而，随着伸展距离增加，分布发生变化，大部分方差由第一个主成分解释。运动速度和最终关节构型均未影响关节之间的耦合。质心分析表明，随着伸展距离增加，质心逐渐向前移动。我们得出结论，随着目标距离增加，伸展和姿势协同作用会耦合在一起，导致手臂、腿部和躯干作为一个功能单元共同协作，使全身向前移动。
