Division of Biokinesiology and Physical Therapy, University of Southern California, Los Angeles, California.
Neuroscience Graduate Program, University of Southern California, Los Angeles, California.
J Neurophysiol. 2022 Oct 1;128(4):808-818. doi: 10.1152/jn.00377.2021. Epub 2022 Aug 10.
A fundamental feature of human locomotor control is the need to adapt walking patterns in response to changes in the environment. For example, when people walk on a split-belt treadmill, which has belts that move at different speeds, they adapt to the asymmetric speed constraints by reducing spatiotemporal asymmetry. Here, we aim to understand the role of balance control as a potential factor driving this adaptation process. We recruited 24 healthy, young adults to adapt to walking on a split-belt treadmill while either holding on to a handrail or walking with free arm swing. We measured whole body angular momentum and step length asymmetry as measures of dynamic balance and spatiotemporal asymmetry, respectively. To understand how changes in intersegmental coordination influenced whole body angular momentum, we also measured segmental angular momenta and the coefficient of cancellation. When participants were initially exposed to the asymmetry in belt speeds, we observed an increase in whole body angular momentum that was due to both an increase in the momentum of individual segments and a reduction in the coefficient of cancellation. Holding on to a handrail reduced the perturbation to asymmetry during the early phase of adaptation and resulted in a smaller aftereffect during early postadaptation. In addition, the stabilization provided by holding on to a handrail led to reductions in the coupling between angular momentum and asymmetry. These results suggest that regulation of dynamic balance is most important during the initial, transient phase of adaptation to walking on a split-belt treadmill. We investigated the role of dynamic balance during adaptation to a split-belt treadmill by measuring whole body angular momentum with or without holding on to a handrail. The initial step length asymmetry and associations between balance and asymmetry reduced when holding on to a handrail during early adaptation. These findings indicate that dynamic balance mostly contributes to the initial phase of adaptation when people are exposed to an asymmetric walking constraint.
人类运动控制的一个基本特征是需要适应环境变化的行走模式。例如，当人们在速度不同的分带跑步机上行走时，他们通过减少时空不对称性来适应不对称的速度限制。在这里，我们旨在了解平衡控制作为潜在因素在这一适应过程中的作用。我们招募了 24 名健康的年轻成年人，让他们在分带跑步机上适应行走，同时可以抓住扶手或自由摆臂。我们分别测量了整体角动量和步长不对称性作为动态平衡和时空不对称性的指标。为了了解节段间协调的变化如何影响整体角动量，我们还测量了节段角动量和取消系数。当参与者最初接触到皮带速度的不对称时，我们观察到整体角动量增加，这是由于单个节段的动量增加和取消系数降低。在适应的早期阶段，抓住扶手减少了对不对称的干扰，导致早期适应后效较小。此外，抓住扶手提供的稳定性导致角动量和不对称之间的耦合减少。这些结果表明，在分带跑步机上行走的适应初始、瞬态阶段，动态平衡的调节最为重要。我们通过测量在分带跑步机上行走时是否抓住扶手来研究动态平衡在适应中的作用。在早期适应过程中抓住扶手时，初始步长不对称性和平衡与不对称之间的关联减少。这些发现表明，当人们接触到不对称的行走约束时，动态平衡主要有助于适应的初始阶段。
