Fling Brett W, Christie Anita, Kamen Gary
Department of Kinesiology, University of Massachusetts-Amherst, 30 Eastman Lane, Amherst, MA 01003, USA.
J Electromyogr Kinesiol. 2009 Oct;19(5):800-9. doi: 10.1016/j.jelekin.2008.06.003. Epub 2008 Aug 8.
Motor unit (MU) synchronization is the simultaneous or near-simultaneous firing of two MUs which occurs more often than would be expected by chance. The present study sought to investigate the effects of exercise training, muscle group, and force level, by comparing the magnitude of synchronization in the biceps brachii (BB) and first dorsal interosseous (FDI) muscles of untrained and strength-trained college-aged males at two force levels, 30% of maximal voluntary contraction (MVC) and 80% MVC. MU action potentials were recorded directly via an intramuscular needle electrode. The magnitude of synchronization was assessed using previously-reported synchronization indices: k', E, and CIS. Synchronization was significantly higher in the FDI than in the BB. Greater synchronization was observed in the strength-trained group with CIS, but not with E or k'. Also, synchronization was significantly greater at 80% MVC than at 30% MVC with E, but only moderately greater with CIS and there was no force difference with k'. Synchronization prevalence was found to be greater in the BB (80.1%) than in the FDI (71.5%). Thus, although the evidence is a bit equivocal, it appears that MU synchronization is greater at higher forces, and greater in strength-trained individuals than in untrained subjects.
运动单位（MU）同步是指两个运动单位同时或近乎同时放电，其发生频率高于偶然预期。本研究旨在通过比较未经训练和经过力量训练的大学年龄男性在两种力量水平（最大自主收缩（MVC）的30%和80%）下肱二头肌（BB）和第一背侧骨间肌（FDI）的同步程度，来研究运动训练、肌肉群和力量水平的影响。通过肌内针电极直接记录运动单位动作电位。使用先前报道的同步指数：k'、E和CIS来评估同步程度。FDI的同步程度显著高于BB。在经过力量训练的组中，CIS显示出更大的同步性，但E或k'没有。此外，E显示在80%MVC时的同步性显著高于30%MVC时，但CIS仅略高，k'没有力量差异。发现BB的同步发生率（80.1%）高于FDI（71.5%）。因此，尽管证据有些模糊，但似乎运动单位同步在较高力量时更大，且在经过力量训练的个体中比未经训练的受试者更大。
