Alon G, Kantor G, Ho H S
School of Medicine, Department of Physical Therapy, University of Maryland, Baltimore, MD 21201.
J Orthop Sports Phys Ther. 1994 Jul;20(1):29-35. doi: 10.2519/jospt.1994.20.1.29.
Recent data have implicated the size of surface electrodes as an important factor affecting peripheral nerve excitation. Therefore, we studied the effects of electrode size on the basic excitatory responses and on stimulus characteristics. Four different sizes of self-adhesive surface electrodes were applied over the medial and lateral gastrocnemius muscle of 20 healthy subjects. The excitatory levels were sensory threshold, motor threshold, pain threshold, and maximally tolerated painful stimulation. Stimulus parameters included a symmetric biphasic waveform, 200 microseconds phase duration, and a pulse repetition rate of 50 pps. Amplitude was increased until the appropriate excitatory response was achieved. At this amplitude level, the computerized recording system collected data of stimulus peak current, peak voltage, and phase charge as well as isometric plantar flexion force. Repeated measure analysis of variance and Newman-Keuls post hoc tests revealed that increasing electrode size significantly decreased voltage but increased current and phase charge magnitudes. With increasing electrode area, the ratios of voltage/current decreased nonlinearly, while the ratios of charge/voltage increased nonlinearly. The comfort of stimulation for the same amount of plantar flexion force improved significantly as electrode size became larger. We concluded that electrode size affects the stimulus parameters, comfort, and force generation associated with electrically induced excitatory responses. Electrode size should be considered an integral part of the attempt to improve subject response to transcutaneous electrical stimulation.
近期数据表明，表面电极的尺寸是影响周围神经兴奋的一个重要因素。因此，我们研究了电极尺寸对基本兴奋反应和刺激特性的影响。将四种不同尺寸的自粘表面电极贴于20名健康受试者的腓肠肌内侧和外侧。兴奋水平包括感觉阈值、运动阈值、疼痛阈值和最大耐受疼痛刺激。刺激参数包括对称双相波形、200微秒的相位持续时间和50次/秒的脉冲重复率。增加振幅直至获得适当的兴奋反应。在此振幅水平下，计算机记录系统收集刺激峰值电流、峰值电压、相位电荷以及等长跖屈力的数据。重复测量方差分析和纽曼-基尔斯事后检验显示，增大电极尺寸会显著降低电压，但会增加电流和相位电荷大小。随着电极面积的增加，电压/电流比呈非线性下降，而电荷/电压比呈非线性增加。对于相同大小的跖屈力，随着电极尺寸变大，刺激的舒适度显著提高。我们得出结论，电极尺寸会影响与电诱导兴奋反应相关的刺激参数、舒适度和力的产生。在试图改善受试者对经皮电刺激的反应时，应将电极尺寸视为一个不可或缺的部分。
