Variations in motor unit recruitment patterns occur within and between muscles in the running rat (Rattus norvegicus)
Variations in motor unit recruitment patterns occur within and between muscles in the running rat (Rattus norvegicus)
复制标题
DOI：
10.1242/jeb.004457
复制
发表时间：
2007-07-01
影响因子：
2.8
通讯作者：
Wakeling, J. M.
中科院分区：
文献类型：
--
作者：
Hodson-Tole, E. F.;Wakeling, J. M.
通常认为运动单位在每块肌肉内遵循一套有序的募集模式，激活发生在最慢到最快的单位中。然而，越来越多的证据表明，招聘模式可能并不总是遵循这样的有序顺序。在这里，我们研究了在水平跑步机上以 40 cm s(-1) 速度跑步的大鼠的踝伸肌内部和踝伸肌之间的运动单位募集模式是否存在变化。过去，很难量化运动过程中运动单位的募集模式。然而，最近小波分析技术的应用使得对运动单位募集的详细分析成为可能。在这里，我们提出了根据肌电信号量化快速和慢速运动单位募集相互作用的方法。肌电数据是从分别代表慢纤维、混合纤维和快纤维群的比目鱼肌、跖肌和腓肠肌内侧收集的，并提供了将肌电频率内容与运动单位招募模式联系起来的良好机会。小波变换之后，主成分分析量化了信号强度和相对频率内容。步幅内不同时间点之间的信号频率内容存在显着差异（P<0.001）。我们针对来自快速和慢速运动单元的主要信号优化了高频和低频小波。对于所有三块肌肉来说，优化小波与信号强度的拟合优度都很高（r(2)> 0.98）。低频段对比目鱼肌信号的拟合效果明显更好（P < 0.001），而高频段对腓肠肌内侧信号的拟合效果明显更好（P < 0.001）。
Motor units are generally considered to follow a set, orderly pattern of recruitment within each muscle with activation occurring in the slowest through to the fastest units. A growing body of evidence, however, suggests that recruitment patterns may not always follow such an orderly sequence. Here we investigate whether motor unit recruitment patterns vary within and between the ankle extensor muscles of the rat running at 40 cm s(-1) on a level treadmill. In the past it has been difficult to quantify motor unit recruitment patterns during locomotion; however, recent application of wavelet analysis techniques has made such detailed analysis of motor unit recruitment possible. Here we present methods for quantifying the interplay of fast and slow motor unit recruitment based on their myoelectric signals. Myoelectric data were collected from soleus, plantaris and medial gastrocnemius muscles representing populations of slow, mixed and fast fibres, respectively, and providing a good opportunity to relate myoelectric frequency content to motor unit recruitment patterns. Following wavelet transformation, principal component analysis quantified signal intensity and relative frequency content. Significant differences in signal frequency content occurred between different time points within a stride ( P< 0.001). We optimised high-and low-frequency wavelets to the major signals from the fast and slow motor units. The goodness-of-fit of the optimised wavelets to the signal intensity was high for all three muscles ( r(2)> 0.98). The low-frequency band had a significantly better fit to signals from the soleus muscle ( P< 0.001), while the high-frequency band had a significantly better fit to the medial gastrocnemius ( P< 0.001).