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.
BACKGROUND: 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. OBJECTIVES: 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. METHODS: 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. RESULTS: 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. CONCLUSION: 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.
背景: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。
目的: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。
方法: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。
结果: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。
结论: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。
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