Random motor unit activation by electrostimulation
Random motor unit activation by electrostimulation
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DOI：
10.1055/s-2007-965075
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发表时间：
2007-11-01
影响因子：
2.5
通讯作者：
Maffiuletti, N. A.
中科院分区：
文献类型：
--
作者：
Jubeau, M.;Gondin, J.;Maffiuletti, N. A.
在表面神经肌肉电刺激和自主激活中，运动单位的参与是否不同仍然是一个悬而未决的问题。这项先导性研究的目的是验证电刺激过程中的运动单位激活是否是非选择性/随机的(即，没有与纤维类型相关的明显序列)，正如Gregory和Bickel 16最近提出的那样。16名健康男性随机进行了股四头肌的次极大等长收缩(10-S持续时间)，在刺激和自愿条件下，分别以最大自主扭矩的20%、40%和60%进行收缩。在收缩过程中，将成对的刺激传递到股神经(抽动插值法)，并比较两种情况下叠加的双重刺激的特征。对于每个扭矩水平，与自愿收缩相比，电刺激时达到峰值扭矩的时间明显更长(p范围=0.05%-0.0002)。此外，当扭矩水平从最大自愿扭矩的20%增加到60%时，自愿试验中的峰值扭矩时间显著减少(p范围=0.03-0.0001)，而在电刺激过程中没有变化。总而言之，根据Hereman的大小原理，肌肉电刺激既不会导致运动单位招募，也不会导致自愿招募顺序的颠倒。在电刺激过程中，肌肉纤维被激活，而没有与纤维类型相关的明显序列。
Whether the involvement of motor units is different between surface neuromuscular electrostimulation and voluntary activation remains an unresolved issue. The aim of this pilot study was to verify if motor unit activation during electrostimulation is nonselective/random (i.e., without obvious sequencing related to fibre type), as recently suggested by Gregory and Bickel 16]. Sixteen healthy men randomly performed submaximal isometric contractions (10-s duration) of the quadriceps femoris muscle at 20, 40 and 60% of maximal voluntary torque under both stimulated and voluntary conditions. During the contractions, paired stimuli were delivered to the femoral nerve (twitch interpolation technique) and the characteristics of the superimposed doublet were compared between the two conditions. For each torque level, time-to-peak torque was significantly longer (p range = 0.05-0.0002) during electrostimulation compared to voluntary contractions. Moreover, time-to-peak torque during voluntary trials decreased significantly when increasing the torque level from 20 to 60% of maximal voluntary torque (p range = 0.03-0.0001), whereas it was unchanged during electrostimulation. In conclusion, over-the-muscle electrostimulation would neither result in motor unit recruitment according to Hermeman's size principle nor would it result in a reversal in voluntary recruitment order. During electrostimulation, muscle fibres are activated without obvious sequencing related to fibre type.