中文摘要：

目的：通过对主动肌和拮抗肌功能转变瞬间肌电平均功率频率的观察，探讨中枢控制因素在决定MPF变化中的独立性作用。方法：10名健康男性志愿者在完成60％MVC强度的疲劳性等长屈肘运动负荷试验后，瞬间转变肌肉工作性质，完成60％MVC强度的疲劳性等长伸肘运动，分别记录肱二头肌和肱三头肌的sEMG信号，观察两次疲劳试验以及瞬间转变过程中肌电MPF等sENG指标变化。结果：等长屈肘和等长伸肘快速转变的瞬间，主动肌和拮抗肌MPF等各项sEMG信号分析指标均发生了显著性改变，表现出明显的跃变现象；无论是转变之前，还是转变之后的等长疲劳试验过程中，主动肌与拮抗肌的MPF、C（n）和％DET均表现出类似的变化规律，而拮抗肌AEMG则维持相对恒定。结论：中枢运动控制是导致疲劳过程中MPF单调递减变化的独立性作用因素，其可能的作用机制是CNS将主动肌与拮抗肌作为一组控制肌群实施同步控制。

英文摘要：

Objective： The purpose of this study was to explore the independent role of central motor control in the alternations of sEMG mean power frequency during elbow flexion to ex- tension transition. Method： 10 healthy male subjects took part in the experiment, which consis- ted of two phase isometric fatigue loading exercise. In the first exercise, the subject performed elbow flexion as soon as possible under the load intensity 60% MVC, then subject performed elbow isometric extension as soon as possible. Both sEMG activities of biceps brachii and tri- ceps brachii were recorded and then mean power frequency and other parameters were calculat- ed. Result ： （ 1 ） During the rapid transition phase, mean power frequency and other sEMG pa- rameters changed significantly. （2）During two phase elbow isometric contractions, both agonist and antagonist muscle showed similar activity patterns of MPF,C（n） and %DET,but AEMG remained relatively constant. Conclusion：The experimental results suggested brain central mo- tor control system displayed an independent role in the alternations of MPF of biceps brachii during fatigue exercise, the possible mechanisms was that both agonist and antagonist were to- tally controlled by the central motor control system.