Department of Health and Kinesiology, Texas A&M University, College Station, TX, 77843-4243, USA.
Eur J Appl Physiol. 2010 Mar;108(5):935-43. doi: 10.1007/s00421-009-1301-5. Epub 2009 Dec 2.
The purpose was to determine the relation between visual feedback gain and variability in force and whether visual gain-induced changes in force variability were associated with frequency-specific force oscillations and changes in the neural activation of the agonist muscle. Fourteen young adults (19-29 years) were instructed to accurately match the target force at 2 and 10% of their maximal voluntary contraction with abduction of the index finger. Force was maintained at specific visual feedback gain levels that varied across trials. Each trial lasted 20 s and the amount of visual feedback was varied by changing the visual gain from 0.5 to 1,474 pixels/N (13 levels; equals approximately 0.001-4.57 degrees ). Force variability was quantified as the standard deviation of the detrended force data. The neural activation of the first dorsal interosseus (FDI) was measured with surface electromyography. The mean force did not vary significantly with the amount of visual feedback. In contrast, force variability decreased from low gains compared to moderate gains (0.5-4 pixels/N: 0.09 +/- 0.04 vs. 64-1,424 pixels/N: 0.06 +/- 0.02 N). The decrease in variability was predicted by a decrease in the power of force oscillations from 0-1 Hz (approximately 50%) and 3-7 Hz (approximately 20%). The activity of the FDI muscle did not vary across the visual feedback gains. These findings demonstrate that in young adults force variability can be decreased with increased visual feedback gain (>64 pixels/N vs. 0.5-4 pixels/N) due to a decrease in the power of oscillations in the force from 0-1 and 3-7 Hz.
目的是确定视觉反馈增益与力变异性之间的关系，以及视觉增益引起的力变异性变化是否与频率特异性力振荡以及激动肌的神经激活变化有关。 14 名年轻人（19-29 岁）被指示用食指外展以 2%和 10%的最大自主收缩力准确匹配目标力。力在跨试验变化的特定视觉反馈增益水平下保持。每个试验持续 20 秒，通过将视觉增益从 0.5 变为 1474 像素/N（13 个级别；大约为 0.001-4.57 度）来改变视觉反馈量。力变异性被量化为去趋势力数据的标准差。第一背侧间骨间肌（FDI）的神经激活通过表面肌电图测量。平均力与视觉反馈量没有显著变化。相比之下，与中增益相比，力变异性从低增益降低（0.5-4 像素/N：0.09 +/- 0.04 对 64-1424 像素/N：0.06 +/- 0.02 N）。力振荡的功率降低（约 50%的 0-1 Hz 和约 20%的 3-7 Hz）预测了变异性的降低。FDI 肌肉的活动在整个视觉反馈增益中没有变化。这些发现表明，在年轻人中，由于 0-1 和 3-7 Hz 的力振荡的功率降低，可以通过增加视觉反馈增益（>64 像素/N 对 0.5-4 像素/N）来降低力变异性。
