Whitall J, Getchell N
Department of Physical Therapy, University of Maryland, Baltimore 21201, USA.
Child Dev. 1995 Oct;66(5):1541-53.
Developmental transitions of complex systems may be studied by selecting (collective) variables that constrain the degrees of freedom for each developmental state. In a dynamical systems approach, the transitions from state to state are engendered through the scaling of contributing subsystems (control parameters). In this study, the locomotor skills of walking and running were compared in newly running infants by observing several likely collective variables including relative stance, estimated pathway of center of mass, and segmental/joint action. 4 children were filmed longitudinally at 5.5, 7.5, and 9.5 months of independent walking and then at 3 years of age. 3 trials per gait were selected for single stride analysis and compared with data from 4 adults. In general, the proposed collective variables showed transitional forms over the first few months of running, indicating a relatively continuous change between the 2 gait forms. Coordination of the knee joint was very similar between gaits and across age, but the ankle joint was less consistent for both gaits in the infants. Relative stance and stride length data indicated that the children could not generate vertical and horizontal displacement. These findings echo those found in newly walking infants and suggest that similar rate-limiting parameters are present for both gaits.
复杂系统的发育转变可以通过选择（集体）变量来研究，这些变量限制了每个发育状态的自由度。在动态系统方法中，状态之间的转变是通过对有贡献的子系统（控制参数）进行缩放来实现的。在本研究中，通过观察几个可能的集体变量，包括相对站立姿势、估计的质心轨迹以及节段/关节动作，对刚开始跑步的婴儿的行走和跑步运动技能进行了比较。对4名儿童在独立行走的5.5、7.5和9.5个月时以及3岁时进行了纵向拍摄。每个步态选择3次试验进行单步分析，并与4名成年人的数据进行比较。总体而言，所提出的集体变量在跑步的最初几个月呈现出过渡形式，表明这两种步态形式之间存在相对连续的变化。不同步态之间以及不同年龄之间膝关节的协调性非常相似，但婴儿在两种步态中踝关节的协调性不太一致。相对站立姿势和步长数据表明，儿童无法产生垂直和水平位移。这些发现与刚开始行走的婴儿的研究结果一致，表明两种步态都存在类似的速率限制参数。
