Different devices for mechano-acoustic muscle vibration became available on the market in the last ten years. Although the use of these vibrators is increasing in research and clinical settings, the features of their stimulation output were never described in literature. In this study we aimed to quantify and compare the stimulation output of the four most widespread pneumatic devices for focal muscle vibration available on the market.

A piezoelectric pressure sensor was used to measure the pressure profile generated by the four selected devices in the following experimental conditions: i) measurement of the output changes associated with variations of the stimulation amplitude for three stimulation frequencies (100 Hz, 200 Hz, and 300 Hz); ii) measurement of the output changes during a 20-min long stimulation at constant frequency (300 Hz) and amplitude; iii) measurement of the output changes associated with the progressive activation of all stimulation channels at constant frequency (200 Hz) for different amplitudes.

The maximum peak-to-peak amplitudes of the pressure waves were in the range 102 mbar - 369 mbar (below the maximum values declared by the different manufacturers). The shape of the pressure waves generated by the four devices was quasi-sinusoidal and asymmetric with respect to the atmospheric pressure. All output features had a remarkable intra- and inter-device variability.

Further studies are required to support the technological improvement of the currently available devices and to focus the issues of vibration effectiveness, limitations, proper protocols, modalities of its application and assessment in neuromuscular training and rehabilitation.

在过去的十年中，市场上出现了不同的机械声学肌肉振动设备。尽管这些振动器在研究和临床环境中的使用越来越多，但其刺激输出的特征从未在文献中描述过。在这项研究中，我们旨在量化和比较市场上可用的四种最广泛的用于焦点肌肉振动的气动设备的刺激输出。

在以下实验条件下，使用压电压力传感器测量由四个选定设备产生的压力分布：i) 测量与三个刺激频率（100 Hz、200 Hz 和 300 Hz）的刺激幅度变化相关的输出变化赫兹）；ii) 在恒定频率 (300 Hz) 和振幅下，在 20 分钟长刺激期间测量输出变化；iii) 测量与所有刺激通道在不同幅度下以恒定频率 (200 Hz) 逐步激活相关的输出变化。

压力波的最大峰峰值幅度在 102 mbar - 369 mbar 范围内（低于不同制造商声明的最大值）。四个装置产生的压力波的形状是准正弦的，并且相对于大气压不对称。所有输出特征都具有显着的设备内和设备间可变性。

需要进一步的研究来支持当前可用设备的技术改进，并关注振动有效性、局限性、适当的协议、其在神经肌肉训练和康复中的应用和评估方式等问题。