Reisman Darcy S, Scholz John P, Schöner Gregor
Biomechanics and Movement Science Graduate Program, University of Delaware, Newark, DE 19716, USA.
J Electromyogr Kinesiol. 2002 Dec;12(6):493-505. doi: 10.1016/s1050-6411(02)00029-9.
We studied similarities and differences in the use of goal-equivalent patterns of joint coordination to stand up and sit down from different support surfaces, performed without vision. Sagittal plane motion of major body segments was measured and joint angles for the left upper and lower extremities and the trunk were calculated. We used a modeling strategy relating motion in the redundant space of the joints to motion of individual performance variables, such as the center of mass (CM) or head, and determined how the variability of joint combinations across trials was structured; i.e. variations in joint combinations leading to a consistent value of a performance variable (goal-equivalent variability) and variations resulting in variability of the performance variable (non goal-equivalent variability). We found the variability of joint combinations to be selectively channeled into goal-equivalent directions, leading to stable horizontal motion of the CM and of the head, during both standing up and sitting down. In contrast, when evaluating the effect of joint combination variability on the control of vertical CM motion, we found differences in the variability components between standing up and sitting down. In general, more variable vertical CM motion occurred. An important finding was an enhanced use of goal-equivalent joint combinations under challenging task conditions, whether standing up or sitting down.
我们研究了在无视觉情况下，从不同支撑面起身和坐下时，关节协调的目标等效模式使用中的异同。测量了主要身体节段的矢状面运动，并计算了左上肢、左下肢和躯干的关节角度。我们采用了一种建模策略，将关节冗余空间中的运动与个体性能变量（如质心（CM）或头部）的运动联系起来，并确定了试验中关节组合的变异性是如何构成的；即导致性能变量一致值的关节组合变化（目标等效变异性）和导致性能变量变异性的变化（非目标等效变异性）。我们发现，在起身和坐下过程中，关节组合的变异性被选择性地引导到目标等效方向，从而使质心和头部实现稳定的水平运动。相比之下，在评估关节组合变异性对垂直质心运动控制的影响时，我们发现起身和坐下之间的变异性成分存在差异。一般来说，垂直质心运动的变异性更大。一个重要发现是，无论是起身还是坐下，在具有挑战性的任务条件下，目标等效关节组合的使用都会增加。
