Wu Mengnan Mary, Brown Geoffrey, Gordon Keith E
Department of Physical Therapy and Human Movement Sciences, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States.
Department of Physical Therapy and Human Movement Sciences, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States; Research Service, Edward Hines Jr. VA Hospital, Hines, IL, United States.
Gait Posture. 2017 Jun;55:191-198. doi: 10.1016/j.gaitpost.2017.04.021. Epub 2017 Apr 26.
To develop effective interventions targeting locomotor stability, it is crucial to understand how people control and modify gait in response to changes in stabilization requirements. Our purpose was to examine how individuals with and without incomplete spinal cord injury (iSCI) control lateral stability in haptic walking environments that increase or decrease stabilization demands. We hypothesized that people would adapt to walking in a predictable, stabilizing viscous force field and unpredictable destabilizing force field by increasing and decreasing feedforward control of lateral stability, respectively. Adaptations in feedforward control were measured using after-effects when fields were removed. Both groups significantly (p<0.05) decreased step width in the stabilizing field. When the stabilizing field was removed, narrower steps persisted in both groups and subjects with iSCI significantly increased movement variability (p<0.05). The after-effect of walking in the stabilizing field was a suppression of ongoing general stabilization mechanisms. In the destabilizing field, subjects with iSCI took faster steps and increased lateral margins of stability (p<0.05). Step frequency increases persisted when the destabilizing field was removed (p<0.05), suggesting that subjects with iSCI made feedforward adaptions to increase control of lateral stability. In contrast, in the destabilizing field, non-impaired subjects increased movement variability (p<0.05) and did not change step width, step frequency, or lateral margin of stability (p>0.05). When the destabilizing field was removed, increases in movement variability persisted (p<0.05), suggesting that non-impaired subjects made feedforward decreases in resistance to perturbations.
为了开发针对运动稳定性的有效干预措施，了解人们如何根据稳定需求的变化来控制和调整步态至关重要。我们的目的是研究患有和未患有不完全脊髓损伤（iSCI）的个体在增加或减少稳定需求的触觉步行环境中如何控制侧向稳定性。我们假设，人们会分别通过增加和减少侧向稳定性的前馈控制，来适应在可预测的稳定粘性力场和不可预测的不稳定力场中行走。当力场移除时，利用后效应来测量前馈控制的适应性。两组在稳定力场中均显著（p<0.05）减小了步幅宽度。当稳定力场移除后，两组的步幅宽度仍保持较窄，且患有iSCI的受试者运动变异性显著增加（p<0.05）。在稳定力场中行走的后效应是对正在进行的一般稳定机制的抑制。在不稳定力场中，患有iSCI的受试者步速加快，侧向稳定裕度增加（p<0.05）。当不稳定力场移除后，步频增加仍持续存在（p<0.05），这表明患有iSCI的受试者进行了前馈适应以增加对侧向稳定性的控制。相比之下，在不稳定力场中，未受损受试者的运动变异性增加（p<0.05），且步幅宽度、步频或侧向稳定裕度均未改变（p>0.05）。当不稳定力场移除后，运动变异性的增加仍持续存在（p<0.05），这表明未受损受试者对扰动的抵抗力进行了前馈降低。
