Delitto A, Rose S J
Phys Ther. 1986 Nov;66(11):1704-7. doi: 10.1093/ptj/66.11.1704.
The purpose of this study was to compare the relative comfort levels of electrical stimulation having different waveforms, but otherwise identical current characteristics, delivered percutaneously to normal quadriceps femoris muscles contracting at the same intensity level. The quadriceps femoris muscles of 20 healthy subjects were stimulated to a torque level 60% of that obtained in a maximal voluntary isometric contraction, using pulsed current with a carrier frequency of 2,500 Hz, at 50 pulses per second of 10-msec pulse duration. Three different waveforms were used: sinusoidal, sawtooth (triangular), and square. The relative comfort level of each electrically elicited contraction for each waveform was determined for each subject using a 20-cm-long visual analog scale. The results showed that no one waveform was most comfortable (least uncomfortable) and the difference was significant in what the subjects perceived to be the most comfortable contraction, regardless of waveform (p less than .01). These results indicate that a subject's perception of discomfort changes as the waveform of stimulation varies and that individual preferences exist for different waveforms. Selection of the most comfortable waveform could prove beneficial when the intensity of muscle stimulation is increased.
本研究的目的是比较经皮向以相同强度水平收缩的正常股四头肌输送具有不同波形但其他电流特性相同的电刺激时的相对舒适度。对20名健康受试者的股四头肌进行刺激，使其达到最大自主等长收缩时所获扭矩水平的60%，使用载波频率为2500Hz、脉冲持续时间为10毫秒、每秒50个脉冲的脉冲电流。采用了三种不同的波形：正弦波、锯齿波（三角形）和方波。使用一个20厘米长的视觉模拟量表，为每个受试者确定每种波形每次电诱发收缩的相对舒适度。结果表明，没有一种波形是最舒适的（最不难受的），而且无论波形如何，受试者认为最舒适的收缩存在显著差异（p小于0.01）。这些结果表明，随着刺激波形的变化，受试者对不适的感知也会改变，并且对于不同波形存在个体偏好。当增加肌肉刺激强度时，选择最舒适的波形可能会有益处。
