Flanders M, Pellegrini J J, Geisler S D
Department of Physiology, University of Minnesota, Minneapolis 55455, USA.
Exp Brain Res. 1996 Jun;110(1):67-79. doi: 10.1007/BF00241376.
The purpose of this study was to fully characterize the timing and intensity of the phasic portion of the electromyographic (EMG) waveform for reaching movements in vertical planes. Electromyographic activity was simultaneously recorded from nine superficial elbow and/or shoulder muscles while human subjects made rapid arm movements. Hand paths comprised 20 directions in a sagittal plane and 20 directions in a frontal plane. In order to focus on the more phasic aspects of muscle activation, estimates of postural EMG activity were subtracted from the EMG traces recorded during rapid reaches. These postural estimates were obtained from activity recorded during very slow reaches to the same targets. After subtraction of this postural activity, agonist or antagonist burst patterns were often observed in the phasic EMG traces. For nearly all muscles and all subjects, the relation between phasic EMG intensity and movement direction was a function with multiple peaks. For all muscles, the timing of phasic EMG bursts varied as a function of movement direction: the data from each muscle exhibited a gradual temporal shift of activity over a certain range of directions. This gradual temporal shift has no obvious correspondence to the mechanical requirements of the task and might represent a neuromuscular control strategy in which burst timing contributes to the specification of movement direction.
本研究的目的是全面描述垂直平面内伸手动作时肌电图（EMG）波形的相位部分的时间和强度特征。在人类受试者进行快速手臂运动时，同时记录了九块浅表肘部和/或肩部肌肉的肌电活动。手部运动轨迹包括矢状面内的20个方向和额状面内的20个方向。为了关注肌肉激活的更多相位方面，从快速伸手过程中记录的EMG迹线中减去姿势性EMG活动的估计值。这些姿势估计值是从非常缓慢地伸手到相同目标时记录的活动中获得的。减去这种姿势活动后，在相位EMG迹线中经常观察到激动剂或拮抗剂爆发模式。对于几乎所有肌肉和所有受试者，相位EMG强度与运动方向之间的关系是一个具有多个峰值的函数。对于所有肌肉，相位EMG爆发的时间随运动方向而变化：每块肌肉的数据在一定方向范围内表现出活动的逐渐时间偏移。这种逐渐的时间偏移与任务所需的机械要求没有明显对应关系，可能代表一种神经肌肉控制策略，其中爆发时间有助于确定运动方向。
