From the Center for Sensorimotor Research, Department of Neurology, Ludwig-Maximilians University, Munich, Germany (JS); and Discipline of Exercise and Sports Science, Faculty of Health Sciences, University of Sydney, Sydney, Australia (CF).
Am J Phys Med Rehabil. 2014 Feb;93(2):146-59. doi: 10.1097/PHM.0000000000000008.
The aim of this study was to investigate the effect of neuromuscular electrical stimulation burst duty cycle (BDC) and current type (sinusoidal alternating current [sAC] vs. rectangular alternating current [rAC]) on the electrically induced isometric torque (EIT) and discomfort. Pulsed current (PC) stimulation, which corresponds to one pulse rAC, was included in testing.
A repeated-measures design was used. The left quadriceps of 22 healthy subjects (mean ± SD age, 33 ± 8 yrs) were stimulated alternately with sAC and rAC current bursts (4-kHz carrier frequency; 71 bursts per second burst frequency) to produce isometric contractions. A range of BDCs were tested for sAC (7%-50%) and rAC (2%-18%) stimulation at fixed intensities while EIT and discomfort were recorded. BDC presentation order was randomized.
Overall, both current types elicited peak EIT at ∼14% BDC (range, 7%-21%). Significantly more EIT was produced by rAC than by sAC stimulation (P < 0.005). Discomfort increased with BDC and was similar for both current types.
The study confirmed previous findings that conventional sAC stimulation (50% BDC) and pulsed current stimulation (rAC with 2% BDC) used in sports and rehabilitation produce similar EIT levels. However, rAC stimulation at low BDC (7%-18%) was more effective (+35% torque produced with similar discomfort) than pulsed current or conventional sAC.
本研究旨在探讨神经肌肉电刺激的脉冲宽度（BDC）和电流类型（正弦交流[AC]与矩形交流[AC]）对电诱发等长收缩扭矩（EIT）和不适的影响。测试中包括了与矩形交流对应的单脉冲脉冲电流（PC）刺激。
采用重复测量设计。22 名健康受试者（平均年龄 ± 标准差，33 ± 8 岁）的左侧股四头肌分别用正弦交流电和矩形交流电脉冲（4-kHz 载波频率；71 个脉冲/秒脉冲频率）交替刺激产生等长收缩。在固定强度下，测试了正弦交流电（7%-50%）和矩形交流电（2%-18%）的一系列 BDC，同时记录 EIT 和不适。BDC 的呈现顺序是随机的。
总的来说，两种电流类型在约 14% BDC 时均能产生峰值 EIT（范围 7%-21%）。矩形交流电刺激产生的 EIT 明显高于正弦交流电刺激（P < 0.005）。不适随 BDC 增加而增加，两种电流类型相似。
本研究证实了之前的发现，即运动和康复中使用的传统正弦交流电刺激（50% BDC）和脉冲电流刺激（2% BDC 的矩形交流电）产生相似的 EIT 水平。然而，低 BDC（7%-18%）的矩形交流电刺激比脉冲电流或传统正弦交流电刺激更有效（产生的扭矩增加 35%，但不适程度相似）。
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