Park Seoung Hoon, Kim Changki, Yacoubi Basma, Christou Evangelos A
Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, FL, USA.
Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, FL, USA.
Hum Mov Sci. 2019 Apr;64:89-100. doi: 10.1016/j.humov.2019.01.009. Epub 2019 Jan 25.
Force variability during steady force tasks is strongly related to low-frequency oscillations (<0.25 Hz) in force. However, it is unknown whether low-frequency oscillations also contribute to the variability of oscillatory force tasks. To address this, twelve healthy young participants (21.08 ± 2.99 years, 6 females) performed a sinusoidal force task at 15% MVC at two different frequencies (0.5 and 1 Hz) with isometric abduction of the index finger. We recorded the force from the index finger and surface EMG from the first dorsal interosseous muscle and quantified the following outcomes: 1) trajectory variability and accuracy; 2) power spectrum of force and EMG bursting below 2 Hz; 3) power spectrum of the interference EMG from 4 to 60 Hz. The trajectory variability and error significantly increased from 0.5 to 1 Hz task (P < 0.01). Increased force oscillations <0.25 Hz contributed to greater trajectory variability and error for both the 0.5 and 1 Hz oscillatory task (R > 0.33; P < 0.05). The <0.25 Hz oscillations in force were positively associated with greater power in the <0.25 Hz for EMG bursting (R > 0.52; P < 0.01). The modulation of the interference EMG from 35 to 60 Hz was a good predictor of the <0.25 Hz force oscillations for both the 0.5 Hz task and 1 Hz task (R > 0.66; P < 0.01). These results provide novel evidence that, similar to steady contractions, low-frequency oscillations of the motor neuron pool appear to be a significant mechanism that controls force during oscillatory force tasks.
在稳定用力任务期间，力的变异性与力的低频振荡（<0.25Hz）密切相关。然而，低频振荡是否也会导致振荡用力任务的变异性尚不清楚。为了解决这个问题，12名健康的年轻参与者（21.08±2.99岁，6名女性）在15%最大自主收缩（MVC）下，以食指等长外展进行了两种不同频率（0.5和1Hz）的正弦用力任务。我们记录了食指的力和第一背侧骨间肌的表面肌电图，并对以下结果进行了量化：1）轨迹变异性和准确性；2）低于2Hz的力和肌电图爆发的功率谱；3）4至60Hz的干扰肌电图的功率谱。轨迹变异性和误差在0.5Hz任务到1Hz任务中显著增加（P<0.01）。<0.25Hz的力振荡增加导致0.5Hz和1Hz振荡任务的轨迹变异性和误差更大（R>0.33；P<0.05）。<0.25Hz的力振荡与肌电图爆发<0.25Hz时更大的功率呈正相关（R>0.52；P<0.01）。对于0.5Hz任务和1Hz任务，35至60Hz干扰肌电图的调制是<0.25Hz力振荡的良好预测指标（R>0.66；P<0.01）。这些结果提供了新的证据，即与稳定收缩类似，运动神经元池的低频振荡似乎是在振荡用力任务期间控制力量的重要机制。
