Lab BioNR, Centre intersectoriel en santé durable, Université du Québec à Chicoutimi, Chicoutimi, QC, Canada.
Institut de recherche Robert-Sauvé en santé et en sécurité de travail, Montréal, QC, Canada.
PLoS One. 2023 Jan 23;18(1):e0280835. doi: 10.1371/journal.pone.0280835. eCollection 2023.
The vibration-induced postural reaction paradigm (VIB-PR) offers a unique way for investigating sensorimotor control mechanisms. Measures of VIB-PR are usually calculated from the whole VIB period, yet recent evidence proposed that distinctive mechanisms are likely at play between the early vs. later phases of the postural reaction.
The present work verified if spatiotemporal analyses of center of pressure (COP) displacements can detect differences between these early/later phases of VIB-PR. Also, we further characterized the intra/inter-individual variability of COP measurements, since the underlying variability of VIB-PR remains largely unexplored.
Twenty young volunteers realized two experimental conditions of bipodal stance with eyes closed: (i) bilateral VIB of tibialis anterior (TIB) and (ii) Achilles' (ACH) tendons. Each condition consisted of five trials and lasted 30 s as follows: 10 s baseline, 10 s VIB and 10 s post-VIB. Linear COP variables (antero-posterior (AP) amplitude & velocity) were computed for both VIB and post-VIB periods using the following time-windows: early 2 s, the later 8 s and the whole 10 s duration. Intra- and inter-individual variability were respectively estimated using the standard error of the measurement and the coefficient of variation. Both variability metrics were obtained using five vs. the first three trials.
Significant contrasts were found between time-windows for both VIB and post-VIB periods. COP variables were generally higher during the early 2 s phase compared to the later 8 s phase for both TIB [mean difference between 8 s- 2 s phases: Amplitude AP = -1.11 ± 1.14 cm during VIB and -2.99 ± 1.31 during post-VIB; Velocity AP = -1.17 ± 0.86 cm/s during VIB and -3.13 ± 1.31 cm/s during post-VIB] and ACH tendons [Amplitude AP = -0.37 ± 0.98 cm during VIB and -3.41 ± 1.20 during post-VIB; Velocity AP = -0.31 ± 0.59 cm/s during VIB and -3.89 ± 1.52 cm/s during post-VIB]. Most within- and between-subject variability scores were below 30% and using three instead of five trials had no impact on variability. VIB-PR patterns were quite similar within a same person, but variable behaviors were observed between individuals during the later phase.
Our study highlights the relevance of identifying and separately analyzing distinct phases within VIB-PR patterns, as well as characterizing how these patterns vary at the individual level.
振动诱发姿势反应范式（VIB-PR）为研究感觉运动控制机制提供了一种独特的方法。VIB-PR 的测量值通常是从整个 VIB 周期计算得出的，但最近的证据表明，在姿势反应的早期和晚期阶段，可能存在不同的机制。
本研究旨在验证压力中心（COP）位移的时空分析是否可以检测 VIB-PR 早期/晚期阶段之间的差异。此外，我们进一步描述了 COP 测量的个体内/个体间变异性，因为 VIB-PR 的潜在变异性在很大程度上仍未得到探索。
20 名年轻志愿者在闭眼双足姿势下进行了两项实验条件：（i）胫骨前肌（TIB）和（ii）跟腱（ACH）双侧 VIB。每个条件包括 5 次试验，持续 30 秒，如下所示：10 秒基线，10 秒 VIB 和 10 秒 VIB 后。使用以下时间窗口计算 VIB 和 post-VIB 期间的线性 COP 变量（前-后（AP）幅度和速度）：早期 2 秒，后期 8 秒和整个 10 秒持续时间。分别使用测量的标准误差和变异系数估计个体内和个体间的变异性。这两个变异性指标都是使用五个试验而不是前三个试验获得的。
在 VIB 和 post-VIB 期间，时间窗口之间存在显著差异。与后期 8 秒相比，TIB [VIB 期间 8 s-2 s 相位之间的平均差异：AP 幅度= -1.11 ± 1.14 cm；VIB 期间 2 s-8 s 相位之间的平均差异：AP 幅度= -2.99 ± 1.31；VIB 期间 AP 速度= -1.17 ± 0.86 cm/s；VIB 期间 2 s-8 s 相位之间的平均差异：AP 速度= -3.13 ± 1.31 cm/s]和 ACH 肌腱 [AP 幅度= -0.37 ± 0.98 cm；VIB 期间 2 s-8 s 相位之间的平均差异：AP 幅度= -3.41 ± 1.20；VIB 期间 AP 速度= -0.31 ± 0.59 cm/s；VIB 期间 2 s-8 s 相位之间的平均差异：AP 速度= -3.89 ± 1.52 cm/s]的 COP 变量通常更高。在后期阶段，个体内和个体间的大多数变异性评分均低于 30%，并且使用三个而不是五个试验对变异性没有影响。VIB-PR 模式在同一个人内非常相似，但在后期阶段，不同个体之间观察到可变行为。
本研究强调了识别和分别分析 VIB-PR 模式中不同阶段以及描述这些模式如何在个体水平上变化的重要性。
