Ivanenko Yuri P, Dominici Nadia, Cappellini Germana, Lacquaniti Francesco
Department of Neuromotor Physiology, IRCCS Fondazione Santa Lucia, Rome, Italy.
J Neurophysiol. 2005 Jul;94(1):754-63. doi: 10.1152/jn.00088.2004.
When a toddler starts to walk without support, gait kinematics and electromyographic (EMG) activity differ from those of older children and the body displays considerable oscillations due to poor equilibrium. Postural instability clearly affects motor patterns in adults, but does instability explain why toddlers walk with a different gait? Here we addressed this question by comparing kinematics and EMGs in toddlers performing their first independent steps with or without hand or trunk support. Hand support significantly improved postural stability and some general gait parameters, reducing percent of falls, step width, lateral hip deviations and trunk oscillations. However, the kinematic and EMG patterns were unaffected by increased postural stability. In particular, the co-variance of the angular motion of the lower limb segments, the pattern of bilateral coordination of the vertical movement of the two hip joints, high variability of the foot path, the elliptic or single peak trajectory of the foot in the swing phase, and characteristic EMG bursts at foot contact remained idiosyncratic of toddler locomotion. Instead the toddler pattern shared fundamental features with adult stepping in place, suggesting that toddlers implement a mixed locomotor strategy, combining forward progression with elements of stepping in place. Furthermore, gait kinematics remained basically unchanged until the occurrence of the first unsupported steps and rapidly matured thereafter. We conclude that idiosyncratic features in newly walking toddlers do not simply result from undeveloped balance control but may represent an innate kinematic template of stepping.
当幼儿开始独立行走时，其步态运动学和肌电图（EMG）活动与大龄儿童不同，由于平衡能力差，身体会出现明显的摆动。姿势不稳定显然会影响成年人的运动模式，但这种不稳定能否解释幼儿为何步态不同呢？在这里，我们通过比较幼儿在有或没有手部或躯干支撑的情况下迈出第一步时的运动学和肌电图，来探讨这个问题。手部支撑显著提高了姿势稳定性和一些一般的步态参数，减少了跌倒百分比、步幅宽度、髋关节外侧偏差和躯干摆动。然而，运动学和肌电图模式并未受到姿势稳定性提高的影响。特别是，下肢各节段角运动的协方差、两个髋关节垂直运动的双侧协调模式、足部轨迹的高变异性、摆动期足部的椭圆形或单峰轨迹，以及足部接触时特有的肌电图爆发，仍然是幼儿行走的独特特征。相反，幼儿的模式与成年人原地踏步有一些基本特征相同，这表明幼儿采用了一种混合的运动策略，将向前推进与原地踏步元素相结合。此外，在首次无支撑行走出现之前，步态运动学基本保持不变，此后迅速成熟。我们得出结论，刚学会走路的幼儿的独特特征并非仅仅源于未发育成熟的平衡控制，而可能代表了一种天生的行走运动学模板。
