Martin B J, Park H S
Dept. of Industrial and Operations Engineering, University of Michigan, Ann Arbor 40109-2117, USA.
Eur J Appl Physiol Occup Physiol. 1997;75(6):504-11. doi: 10.1007/s004210050196.
The influence of vibration frequency (40, 80, 100, 120, 150, or 200 Hz) at selected displacement amplitudes (0.2, 0.3 mm) on tonic vibration reflex (TVR) characteristics was investigated. The degree of synchronization of motor unit activity with vibratory stimuli in ten humans was determined using the electromyographic (EMG) activity of the finger and wrist flexor muscles when vibration was applied to the distal tendons of the hand flexor muscles. The EMG spectral analysis indicates that harmonic and subharmonic motor unit synchronization mechanisms contribute to the modulation of the amplitude of the TVR as the vibration frequency increases. Harmonic synchronization decreases while subharmonic synchronization increases as vibration frequency increases. It is suggested that the synchronization process influences muscle fatigue, since it forces the driving of motor units, leading to a decrease in contraction efficiency. This phenomenon most probably results from an impairment of excitation-contraction coupling. High-frequency vibration (> 150 Hz) tends to induce less motor unit synchronization in a frequency range beyond the known mechanical resonance of biological tissues. The findings of this study may be applied to the design of hand-held power tools, since their vibration triggers the TVR in active muscles.
研究了在选定的位移幅度（0.2、0.3毫米）下，振动频率（40、80、100、120、150或200赫兹）对强直性振动反射（TVR）特征的影响。当对手部屈肌的远端肌腱施加振动时，通过手指和腕部屈肌的肌电图（EMG）活动，确定了十名受试者中运动单位活动与振动刺激的同步程度。EMG频谱分析表明，随着振动频率的增加，谐波和次谐波运动单位同步机制有助于调节TVR的幅度。随着振动频率增加，谐波同步减少，次谐波同步增加。有人认为，同步过程会影响肌肉疲劳，因为它迫使运动单位驱动，导致收缩效率降低。这种现象很可能是由兴奋-收缩偶联受损引起的。在超出生物组织已知机械共振的频率范围内，高频振动（>150赫兹）往往会诱导较少的运动单位同步。本研究的结果可能应用于手持式电动工具的设计，因为它们的振动会触发活跃肌肉中的TVR。
