2 COMPONENTS OF MUSCLE ACTIVATION - SCALING WITH THE SPEED OF ARM MOVEMENT
2 COMPONENTS OF MUSCLE ACTIVATION - SCALING WITH THE SPEED OF ARM MOVEMENT
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DOI：
10.1152/jn.1992.67.4.931
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发表时间：
1992-04-01
影响因子：
2.5
通讯作者：
HERRMANN, U
中科院分区：
文献类型：
--
作者：
FLANDERS, M;HERRMANN, U
1.肌肉活动的时间波形与手臂运动的速度有关。速度用固定幅度运动的持续时间或“运动时间”来表示。“2.人类受试者在三维空间中移动他们的手臂到目标。右臂从标准的初始位置开始，一划而过，直奔目标。目标被放置在垂直平面的不同方向。手臂动作包括肩关节和肘关节的旋转.受试者被要求改变他们的运动速度。在大多数实验中，不同运动时间的试验是随机排序的。其中一个实验还包括随机穿插的静态试验，其中受试者将手臂保持在初始姿势，最终姿势或两个极端之间的中间位置。肌电图（EMG）活动记录从几个浅表肘部和/或肩部肌肉。校正EMG记录的时基针对运动时间进行归一化，使得来自具有各种速度的运动的记录被压缩以对齐运动的结束时间。主成分分析表明，压缩后的肌电信号波形可以用PC 1和PC 2波形的和来描述，每个单独的肌电信号波形可以用这两个分量的加权和来近似. PC 1加权系数以与运动时间的单调关系按比例缩小，使得最快的运动对应于大的正加权系数，而最慢的运动对应于小的正加权系数。PC 2加权系数表现出类似的单调缩放，但值的范围从正到负。进一步的分析表明，这两个分量可以在数学上转换为具有恒定加权系数的强直波形和具有正加权系数的相位波形，该相位波形随运动时间按比例缩小。EMG记录的幅度缩放不能由单个分量描述，而是需要两个单独分量的总和。强直分量可以对应于抵消重力所需的力元素，因为该元素的大小不与运动速度成比例。相位分量可以对应于二次缩放以产生速度的线性增加的力元素。
1. The temporal waveform of muscle activity was related to the speed of arm movement. Speed was expressed in terms of the duration of a fixed amplitude movement or the "movement time." 2. Human subjects moved their arms to targets in three-dimensional space. The right arm started at a standard initial position and moved directly to the target in a single stroke. The targets were placed in various directions in a vertical plane. The arm movements consisted of shoulder and elbow rotations.3. Subjects were required to vary the speed of their movements. In most of the experiments, trials with different movement times were randomly ordered. One of the experiments also included randomly interspersed static trials, in which the subject held the arm still at the initial posture, the final posture, or halfway between the two extremes.4. Electromyographic (EMG) activity was recorded from several superficial elbow and/or shoulder muscles. The time base of rectified EMG records was normalized for movement time such that records from movements with various speeds were compressed to align the ending times of the movements.5. A principal component (PC) analysis is revealed that the compressed EMG waveforms could be described by a summation of PC1 and PC2 waveforms, each individual EMG waveform was approximated by a weighted sum of these two components.6. The PC1 weighting coefficients scaled down in a monotonic relationship with movement time such that the fastest movement corresponded to a large positive weighting coefficient and the slowest movement corresponded to a small positive weighting coefficient. The PC2 weighting coefficients exhibited a similar monotonic scaling, but the values ranged from positive to negative. Further analysis demonstrated that these two components can be mathematically transformed into a tonic waveform with a constant weighting coefficient and a phasic waveform with positive weighting coefficients that scale down with movement time.7. The amplitude scaling of EMG records cannot be described by a single component, but instead requires a summation of two separate components. The tonic component may correspond to the force element needed to counteract gravity, because the magnitude of this element does not scale with movement speed. The phasic component may correspond to the force element that scales quadratically to produce a linear increase in velocity.