Fatigue induced by intermittent maximal voluntary contractions is associated with significant losses in muscle output but limited reductions in functional MRI-measured brain activation level
Fatigue induced by intermittent maximal voluntary contractions is associated with significant losses in muscle output but limited reductions in functional MRI-measured brain activation level
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DOI：
10.1016/j.brainres.2005.01.059
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发表时间：
2005-04-08
期刊：
影响因子：
2.9
通讯作者：
Yue, GH
中科院分区：
文献类型：
--
作者：
Liu, JZ;Zhang, LD;Yue, GH
本研究的主要目的是表征疲劳任务中涉及手指屈肌重复性最大自愿收缩（MVC）的大脑激活模式。14名年轻、健康的人类参与者进行了类似100次握力MVCs（每次2秒收缩后休息1秒），同时用功能性磁共振成像（fMRI）对他们的大脑进行成像。在疲劳任务结束时，屈指的握力和肌电图（EMG）逐渐下降到初始值的40%左右，表明发生了明显的肌肉疲劳。相比之下，初级（感觉运动）、次级（辅助运动）和联合（前额叶和扣带）运动功能皮层的fMRI信号水平在整个疲劳任务中没有明显变化（尽管初级感觉运动皮层的信号有明显的下降趋势）。在最近发表的一份报告中，间歇握力MVC任务的fMRI数据与2分钟持续握力MVC任务的fMRI数据有显著不同，在2分钟持续握力MVC任务中，fMRI测量的整体大脑激活水平明显较低，与力和肌电的线性下降相比，呈先增加后减少的模式。这些结果支持了这样的观点，即运动皮质中心控制重复性和连续肌肉收缩的任务是不同的，并且在最大自愿收缩引起的肌肉疲劳过程中，大脑和肌肉的信号变化存在脱钩。(c) 2005 Elsevier B.V.版权所有
The main purpose of this study was to characterize brain activation patterns during a fatigue task involving repetitive maximal Voluntary contractions (MVC) of finger flexor muscles. Fourteen young, healthy human participants performed similar to 100 handgrip MVCs (each 2-s contraction was followed by a 1-s rest) while their brain was imaged by functional MRI (fMRI). The handgrip force and electromyograms (EMG) of the finger flexors declined progressively to about 40% of the initial values at the end of the fatigue task, suggesting that significant muscle fatigue had occurred. In contrast, the level of the fMRI signal in the primary (sensorimotor), secondary (supplementary motor), and association (prefrontal and cingulate) motor-function cortices did not change significantly throughout the fatigue task (although the signal of the primary sensorimotor cortex showed a clear trend of decline). The fMRI data from the task of intermittent handgrip MVCs differed dramatically from those obtained in a 2-min sustained handgrip MVC published in a recent report, in which the overall fMRI-measured brain activation level was substantially lower and followed an increase-then-decrease pattern compared to the linear decreases in force and EMG. These results support the notion that the motor cortical centers control the tasks of repetitive and continuous muscle contractions differently and that there is a decoupling in the signal changes of the brain and muscles during muscle fatigue processes induced by maximal voluntary contractions. (c) 2005 Elsevier B.V. All rights reserved.