Zhao Yun, Yan Yanying, Zhang Xiaoling, Xie Guanghui, Yang Renqaing, Zou Shuaidong, Gao Fengmei, Sun Wencheng
School of Smart Health, Chongqing Polytechnic University of Electronic Technology, Chongqing, China.
Front Hum Neurosci. 2025 Jul 28;19:1629003. doi: 10.3389/fnhum.2025.1629003. eCollection 2025.
Neuromuscular electrical stimulation (NMES) is an effective tool to improve motor activation of patients with motor dysfunction. However, to enhance the cortical activities induced by NMES, the corresponding strategies should be carefully designed with optimal stimulation parameters. The aim of the present study is to investigate whether the pulse assignment with wide-pulse-based Variable Frequency Trains improves sensorimotor cortical excitability.
A block-designed experiment was conducted with NMES delivering current to right biceps brachii muscle in nine healthy right-handed adults to evoke repetitive elbow flexion under similar kinetic parameters ( > 0.05). A new NMES pattern with the combination of wide-pulse and Variable Frequency Trains (wDFT, variable-frequency trains with 2-let frequency train) was set to compare with other NMES patterns, i.e., variable-frequency trains with narrow-pulse (nVFT, 8-let frequency train), constant-frequency trains with narrow-pulse (nCFT, one pulse), and CFT with wide-pulse (wCFT, one pulse). The excitability levels of sensorimotor regions were investigated based on beta event-related desynchronization (ERD) analysis.
Although evoking similar elbow flexion movements, variable-frequency trains (VFT) could induce stronger cortical activities than constant-frequency trains (CFT). Moreover, the sensorimotor cortex responded significantly more preferably to the dual 500 μs wide pulse VFT (wDFT) stimulation pattern ( < 0.05). In general, VFT induced higher amplitudes and descending slopes of beta ERD than CFT did during evoking elbow flexion movements, among which wDFT induced the highest beta ERD intensity and its descending slope ( < 0.05). In addition, the current efficiency of VFT to modulate sensorimotor cortical activities was higher than that of CFT pattern.
The VFT pattern, especially dual 500 μs wide pulse VFT, could enhance sensorimotor cortical excitability, and the central neural activities improvements may attribute to the fact that more afferent fibers are effectively activated. Therefore, our findings indicated the high potential of utilizing DFT with wide pulses to optimize NMES applications in motor rehabilitation.
神经肌肉电刺激（NMES）是改善运动功能障碍患者运动激活的有效工具。然而，为增强NMES诱导的皮质活动，应精心设计相应策略并设置最佳刺激参数。本研究旨在探究基于宽脉冲的可变频率序列的脉冲分配是否能提高感觉运动皮质兴奋性。
对9名右利手健康成年人进行了一项区组设计实验，通过NMES向右侧肱二头肌输送电流，在相似动力学参数下（>0.05）诱发重复性肘关节屈曲。设置一种新的宽脉冲与可变频率序列相结合的NMES模式（wDFT，2字母频率序列的可变频率序列），并与其他NMES模式进行比较，即窄脉冲可变频率序列（nVFT，8字母频率序列）、窄脉冲恒定频率序列（nCFT，单脉冲）和宽脉冲CFT（wCFT，单脉冲）。基于β事件相关去同步化（ERD）分析研究感觉运动区域的兴奋性水平。
尽管诱发了相似的肘关节屈曲运动，但可变频率序列（VFT）比恒定频率序列（CFT）能诱导更强的皮质活动。此外，感觉运动皮质对双500μs宽脉冲VFT（wDFT）刺激模式的反应明显更优（<0.05）。总体而言，在诱发肘关节屈曲运动期间，VFT诱导的β ERD幅度和下降斜率高于CFT，其中wDFT诱导的β ERD强度及其下降斜率最高（<0.05）。此外，VFT调节感觉运动皮质活动的电流效率高于CFT模式。
VFT模式，尤其是双500μs宽脉冲VFT，可增强感觉运动皮质兴奋性，中枢神经活动的改善可能归因于更多传入纤维被有效激活这一事实。因此，我们的研究结果表明利用宽脉冲DFT优化NMES在运动康复中的应用具有很高潜力。
