Human Neurophysiology Laboratory, Faculty of Kinesiology, Sport, and Recreation, University of Alberta, AB T6G 2H9, Canada.
Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB T6G 2E1, Canada.
Appl Physiol Nutr Metab. 2020 Sep;45(9):948-956. doi: 10.1139/apnm-2019-0851. Epub 2020 Feb 11.
Interleaved neuromuscular electrical stimulation (iNMES) involves alternating stimulus pulses between the tibialis anterior muscle and common peroneal nerve. The current investigation aimed to characterize the relationship between contraction amplitude, motor unit (MU) "overlap", and contraction fatigability during iNMES. It was hypothesized that as iNMES generates progressively larger contractions, more MUs would be recruited from both sites (i.e., more MU overlap), resulting in more fatigability for larger than smaller contractions. Fourteen participants completed 3 sessions. Fatigability was assessed as the decline in torque over 180 contractions (0.3 s "on", 0.7 s "off") when iNMES was delivered to produce initial contractions of ∼5%, 15%, or 30% of a maximal voluntary contraction. Although MU overlap increased significantly with contraction amplitude, the relative (percent) decline in torque was not different between the contraction amplitudes and torque declined on average by 23%. Contraction fatigability was not significantly correlated with either MU overlap or initial contraction amplitude. In conclusion, iNMES can produce fatigue-resistant contractions across a functionally-meaningful range of contraction amplitudes for rehabilitation. Interleaved neuromuscular electrical stimulation progressively recruits MUs as contraction amplitude increases. However, the relative amount of fatigability of recruited MUs was not different as contraction amplitude increased. This suggests iNMES can be used effectively to produce fatigue-resistant and functionally meaningful contractions.
交错神经肌肉电刺激（iNMES）涉及在前胫骨肌和普通腓神经之间交替刺激脉冲。本研究旨在描述 iNMES 期间收缩幅度、运动单位（MU）“重叠”和收缩疲劳之间的关系。假设随着 iNMES 产生逐渐增大的收缩，更多的 MU 将从两个部位募集（即，更多的 MU 重叠），从而导致较大的收缩比较小的收缩更容易疲劳。14 名参与者完成了 3 次会议。疲劳性通过 iNMES 产生初始收缩约 5%、15%或 30%的最大随意收缩时，在 180 次收缩（0.3 s“开”，0.7 s“关”）过程中扭矩的下降来评估。尽管 MU 重叠随着收缩幅度显著增加，但相对（百分比）扭矩下降在收缩幅度之间没有差异，扭矩平均下降 23%。收缩疲劳性与 MU 重叠或初始收缩幅度均无显著相关性。总之，iNMES 可以在具有功能意义的收缩幅度范围内产生抗疲劳收缩，用于康复。交错神经肌肉电刺激随着收缩幅度的增加逐渐募集 MU。然而，随着收缩幅度的增加，募集 MU 的相对疲劳程度没有差异。这表明 iNMES 可以有效地用于产生抗疲劳和具有功能意义的收缩。
