Department of Health and Sport Science, University of Dayton, Dayton, OH, USA.
Department of Kinesiology and Health, Georgia State University, Atlanta, GA, USA.
Clin Biomech (Bristol). 2021 Jan;81:105235. doi: 10.1016/j.clinbiomech.2020.105235. Epub 2020 Nov 14.
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.
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.
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.
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.
全身振动（WBV）已成为一种改善残疾儿童运动功能和骨骼生长的潜在干预模式。然而，大多数证据来自成人研究。了解残疾和非残疾儿童对不同 WBV 条件的反应机制至关重要。本研究旨在系统研究 6-11 岁正常发育儿童对不同 WBV 频率和振幅的急性生物力学和神经肌肉反应。
17 名受试者参与了这项研究（平均年龄 8.7 岁，10 名男性/7 名女性）。总共呈现了六种交替侧倾的 WBV 条件，结合了三种频率（20、25 和 30 Hz）和两种振幅（1 和 2 毫米），持续一分钟。我们通过运动捕捉标记的平均整流加速度来估计 WBV 期间垂直加速度在身体各节段之间的传递，以及肌电图来测量下半身肌肉激活。在 WBV 之后，受试者进行了反跳跳以评估神经肌肉促进作用。
在所有条件下，垂直加速度从脚踝到头部逐渐降低，在脚踝到膝盖处的阻尼最大。在身体各节段中，高振幅下的加速度传递低于低振幅，随着频率的增加，膝盖降低了加速度传递。此外，肌肉激活在 WBV 期间通常随着频率的增加而增加。WBV 后跳跃高度或肌肉激活没有变化。
WBV 很可能是一种安全的干预模式，适用于正常发育的儿童。对于残疾和非残疾儿童，适当的 WBV 干预设计应考虑 WBV 频率和振幅。
