Wierzbicka M M, Cros D P, Logigian E L
Spinal Cord Injury Service, West Roxbury VA Medical Center, MA, USA.
Electromyogr Clin Neurophysiol. 1998 Sep;38(6):349-54.
The purpose of this study was to investigate whether the central nervous system (CNS) motor program subserving most-rapid voluntary force pulse generation is modified according to the level of agonist muscle load maintained prior to the pulse. Five normal subjects produced most-rapid force pulses to a target of 20% maximum voluntary force (MVF) above different levels of steady tonic contraction. Time to reach peak force, the first agonist burst duration and area were relatively constant for loads up to approximately 40% of MVF and then increased substantially with larger loads. These results indicate that the CNS adjusts agonist burst amplitude and duration in order to accomplish the same rapid motor task depending on the load. It is argued that these adjustments are necessary to compensate for physiological limitations of motor unit behavior and non-linearity between EMG activity and phasic force output.
本研究的目的是调查，在产生最快速的随意力脉冲时，中枢神经系统（CNS）运动程序是否会根据脉冲之前所维持的主动肌负荷水平而发生改变。五名正常受试者在不同水平的持续强直收缩之上，向最大随意力（MVF）的20%这一目标产生最快速的力脉冲。对于高达约40% MVF的负荷，达到峰值力的时间、首次主动肌爆发持续时间和面积相对恒定，然后随着负荷增大而大幅增加。这些结果表明，中枢神经系统会调整主动肌爆发的幅度和持续时间，以便根据负荷完成相同的快速运动任务。有人认为，这些调整对于补偿运动单位行为的生理限制以及肌电图活动与相位力输出之间的非线性是必要的。
