Background

Whole-body vibration (WBV) has emerged as a potential intervention paradigm for improving motor function and bone growth in children with disabilities. However, most evidence comes from adult studies. It is critical to understand the mechanisms of children with and without disabilities responding to different WBV conditions. This study aimed to systematically investigate the acute biomechanical and neuromuscular response in typically developing children aged 6–11 years to varying WBV frequencies and amplitudes.

Methods

Seventeen subjects participated in this study (mean age 8.7 years, 10 M/7F). A total of six side-alternating WBV conditions combining three frequencies (20, 25, and 30 Hz) and two amplitudes (1 and 2 mm) were randomly presented for one minute. We estimated transmission of vertical acceleration across body segments during WBV as the average rectified acceleration of motion capture markers, as well as lower-body muscle activation using electromyography. Following WBV, subjects performed countermovement jumps to assess neuromuscular facilitation.

Findings

Vertical acceleration decreased from the ankle to the head across all conditions, with the greatest damping occurring from the ankle to the knee. Acceleration transmission was lower at the high amplitude than at the low amplitude across body segments, and the knee decreased acceleration transmission with increasing frequency. In addition, muscle activation generally increased with frequency during WBV. There were no changes in jump height or muscle activation following WBV.

Interpretation

WBV is most likely a safe intervention paradigm for typically developing children. Appropriate WBV intervention design for children with and without disabilities should consider WBV frequency and amplitude.

中文翻译：

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全身振动对儿童加速传递和跳跃性能的急性影响

背景

全身振动（WBV）已成为改善残疾儿童运动功能和骨骼生长的潜在干预范例。但是，大多数证据来自成人研究。了解残疾儿童和非残疾儿童对不同WBV条件的反应机制至关重要。这项研究旨在系统地研究6-11岁典型发育中儿童对不同WBV频率和幅度的急性生物力学和神经肌肉反应。

方法

17名受试者参加了这项研究（平均年龄8.7岁，10 M / 7F）。一分钟内，总共随机出现了六个交替的WBV条件，这些条件组合了三个频率（20、25和30 Hz）和两个振幅（1和2 mm）。我们估计了WBV期间跨身体各个部分的垂直加速度的传输，作为运动捕捉标记的平均校正加速度，以及使用肌电图的下半身肌肉激活。WBV后，受试者进行反运动跳跃以评估神经肌肉促进作用。

发现

在所有情况下，从脚踝到头部的垂直加速度都会降低，从脚踝到膝盖的最大阻尼会发生。跨身体段，高振幅下的加速度传递比低振幅下的加速度传递低，并且膝盖随着频率增加而减小了加速度传递。此外，在WBV期间，肌肉激活通常随频率增加。WBV后跳跃高度或肌肉激活没有变化。

解释

对于典型的发育中儿童，WBV最有可能是一种安全的干预范例。针对残疾儿童和非残疾儿童的适当WBV干预设计应考虑WBV的频率和幅度。