Architectural Changes in Superficial and Deep Compartments of the Tibialis Anterior During Electrical Stimulation Over Different Sites
Architectural Changes in Superficial and Deep Compartments of the Tibialis Anterior During Electrical Stimulation Over Different Sites
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DOI：
10.1109/tnsre.2020.3027037
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发表时间：
2020-11-01
影响因子：
4.9
通讯作者：
Botter, Alberto
中科院分区：
文献类型：
--
作者：
Carbonaro, Marco;Seynnes, Olivier;Botter, Alberto
电刺激被广泛应用于康复治疗，以防止肌肉无力，帮助神经功能缺陷的恢复。然而，由于非生理性运动单位(MU)的招募，肌肉疲劳的快速发展限制了它的应用。这一问题可以通过交叉肌腹(MSTim)和神经刺激(NSTim)在不同MU组之间分配临时招募来缓解。为了有效，这种方法需要两种刺激方式来激活最小重叠的MU组。在这篇论文中，我们通过研究胫骨前肌(TA)浅层和深层的结构变化，研究了mSTim和nStim MU募集的空间差异。我们使用超声成像来测量肌肉厚度、羽状角和纤维长度在最大力量的15%和25%的mSTim、nSTim和自愿(Vol)收缩期间的变化。在这两个收缩水平上，nSTim在深部和浅部引起的结构变化与Vol中观察到的相似。取而代之的是，与nSTim和Vol相比，在mStim期间，浅层神经束经历了更大的变化，无论是在绝对大小上还是在间隔之间的相对差异上。这些观察结果表明，与Vol相似，nStim导致整个肌肉体积内分布的MU募集，而mSTim优先激活浅层肌层。NStim和mStim空间募集的差异表明不同的MU群体参与其中，这证明了基于交叉神经/肌肉刺激的策略在电诱导TA收缩时减轻肌肉疲劳的合理性。
Electrical stimulation is widely used in rehabilitation to prevent muscle weakness and to assist the functional recovery of neural deficits. Its application is however limited by the rapid development of muscle fatigue due to the non-physiological motor unit (MU) recruitment. This issue can be mitigated by interleaving muscle belly (mStim) and nerve stimulation (nStim) to distribute the temporal recruitment among different MU groups. To be effective, this approach requires the two stimulation modalities to activate minimally-overlapped groups of MUs. In this manuscript, we investigated spatial differences between mStim and nStim MU recruitment through the study of architectural changes of superficial and deep compartments of tibialis anterior (TA). We used ultrasound imaging to measure variations in muscle thickness, pennation angle, and fiber length during mStim, nStim, and voluntary (Vol) contractions at 15% and 25% of the maximal force. For both contraction levels, architectural changes induced by nStim in the deep and superficial compartments were similar to those observed during Vol. Instead, during mStim superficial fascicles underwent a greater change compared to those observed during nStim and Vol, both in absolute magnitude and in their relative differences between compartments. These observations suggest that nStim results in a distributed MU recruitment over the entire muscle volume, similarly to Vol, whereas mStim preferentially activates the superficial muscle layer. The diversity between spatial recruitment of nStim and mStim suggests the involvement of different MU populations, which justifies strategies based on interleaved nerve/muscle stimulation to reduce muscle fatigue during electrically-induced contractions of TA.