Department of Physical Therapy, Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.
Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Turin, Italy.
Eur J Appl Physiol. 2020 Jun;120(6):1319-1330. doi: 10.1007/s00421-020-04364-y. Epub 2020 Apr 15.
Postural reactions (PR) of standing subjects have been mostly investigated in response to platform displacements or body perturbations of fixed magnitude. The objective of this study was to investigate the relationship between PR and the peak force and impulse of the perturbation.
In ten healthy young men, standing balance was challenged by anteriorly directed perturbations (peak force: 20-60 N) delivered to the back, at the lumbar (L) or inter-scapular (IS) level, by means of a manual perturbator equipped with a force sensor. Postural reactions as expressed by the displacement of the center of pressure (CoP) were recorded using a force platform. Two sets of 20 randomly ordered perturbations (10 to each site) were delivered in two separate testing sessions.
The magnitude of CoP response (∆CoP) was better correlated with the impulse (I) than with the peak force of the perturbation. The normalized response, ∆CoP = ∆CoP/I, exhibited good reliability (ICCs of 0.93 for IS and 0.82 for L), was higher with IS than with L perturbations (p < 0.01), and was significantly correlated with the latency of CoP response: r = 0.69 and 0.71 for IS and L, respectively.
These preliminary findings support the concept that manually delivered perturbations can be used to reliably assess individual PR and that ∆CoP may effectively express a relevant aspect of postural control.
站立受试者的姿势反应（PR）主要是在响应平台位移或固定幅度的身体扰动时进行研究的。本研究的目的是研究 PR 与扰动的峰值力和冲量之间的关系。
在 10 名健康的年轻男性中，通过手动扰动器（配备力传感器）向后、在腰部（L）或肩胛间（IS）水平向背部施加向前定向的扰动（峰值力：20-60N）来挑战站立平衡。使用力平台记录姿势反应，即压力中心（CoP）的位移。在两个单独的测试会话中，以 20 个随机顺序的扰动（每个部位 10 个）的两组进行测试。
CoP 响应（∆CoP）的幅度与扰动的冲量（I）比与峰值力更好相关。归一化响应，∆CoP=∆CoP/I，表现出良好的可靠性（IS 的 ICC 为 0.93，L 的 ICC 为 0.82），IS 比 L 扰动更高（p<0.01），并且与 CoP 响应的潜伏期显著相关：分别为 IS 和 L 的 r=0.69 和 0.71。
这些初步发现支持这样的概念，即手动施加的扰动可以可靠地评估个体的 PR，并且 ∆CoP 可以有效地表达姿势控制的一个相关方面。
