Key Laboratory of Biorheological Science and Technology, Ministry of Education, Bioengineering College, Chongqing University, Chongqing 400044, China.
Chongqing Engineering Research Center of Medical Electronics Technology, Chongqing 400044, China.
Sensors (Basel). 2019 Jan 29;19(3):555. doi: 10.3390/s19030555.
The study aims to explore the spatial distribution of multi-tendinous muscle modulated by central nervous system (CNS) during sustained contraction. Nine subjects were recruited to trace constant target forces with right index finger extension. Surface electromyography (sEMG) of extensor digitorum (ED) were recorded with a 32-channel electrode array. Nine successive topographic maps (TM) were obtained. Pixel wise analysis was utilized to extract subtracted topographic maps (STM), which exhibited inhomogeneous distribution. STMs were characterized into hot, warm, and cool regions corresponding to higher, moderate, and lower change ranges, respectively. The relative normalized area (normalized to the first phase) of these regions demonstrated different changing trends as rising, plateauing, and falling over time, respectively. Moreover, the duration of these trends were found to be affected by force level. The rising/falling periods were longer at lower force levels, while the plateau can be achieved from the initial phase for higher force output (45% maximal voluntary contraction). The results suggested muscle activity reorganization in ED plays a role to maintain sustained contraction. Furthermore, the decreased dynamical regulation ability to spatial reorganization may be prone to induce fatigue. This finding implied that spatial reorganization of muscle activity as a regulation mechanism contribute to maintain constant force production.
本研究旨在探索中枢神经系统（CNS）在持续收缩过程中对多肌腱肌肉的空间分布的调节作用。招募了 9 名被试者，让他们用右食指伸展来追踪恒定的目标力。用 32 通道电极阵列记录伸指肌（ED）的表面肌电图（sEMG）。获得了 9 个连续的地形图（TM）。利用像素分析提取了具有不均匀分布的差地形图（STM）。STM 可分为热点、暖区和冷区，分别对应较高、中等和较低的变化范围。这些区域的相对归一化面积（归一化为第一阶段）随时间呈现出不同的变化趋势，分别为上升、平稳和下降。此外，发现这些趋势的持续时间受到力水平的影响。力水平较低时，上升/下降期较长，而较高的力输出（45%最大自主收缩）可以从初始阶段达到平稳期。研究结果表明，ED 中的肌肉活动重组在维持持续收缩中发挥作用。此外，肌肉活动空间重组的动态调节能力下降可能容易导致疲劳。这一发现表明，肌肉活动的空间重组作为一种调节机制有助于维持恒定的力量产生。
