Background

Individuals with chronic low back pain (CLBP) commonly present with increased trunk muscle fatigability; typically assessed as reduced time to task failure during non-functional isometric contractions. Less is known about the specific neuromuscular responses of individuals with CLBP during dynamic fatiguing tasks. We investigate the regional alteration in muscle activation and peak torque exertion during a dynamic isokinetic fatiguing task in individuals with and without CLBP.

Methods

Electromyography (EMG) was acquired from the lumbar erector spinae unilaterally of 11 asymptomatic controls and 12 individuals with CLBP, using high-density EMG (13 × 5 grid of electrodes). Seated in an isokinetic dynamometer, participants performed continuous cyclic trunk flexion-extension at 60^o/s until volitional exhaustion.

Findings

Similar levels of muscle activation and number of repetitions were observed for both groups (p > 0.05). However, the CLBP group exerted lower levels of peak torque for both flexion and extension moments (p < 0.05). The centre of lumbar erector spinae activity was shifted cranially in the CLBP group throughout the task (p < 0.05), while the control participants showed a more homogenous distribution of muscle activity.

Interpretation

People with CLBP displayed altered and potentially less efficient activation of their lumbar erector spinae during a dynamic fatiguing task. Future studies should consider using high-density EMG biofeedback to optimise the spatial activation of the paraspinal musculature in people with low back pain (LBP).

中文翻译：

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动态等速运动性疲劳过程中有或没有慢性下腰痛的个体的腰直肌脊柱肌肉活动的空间分布

背景

患有慢性下腰痛（CLBP）的人通常表现出躯干肌肉易疲劳性增加；通常认为是在无功能的等距收缩过程中减少了完成任务的时间。在动态疲劳训练过程中，患有CLBP的个体的特定神经肌肉反应知之甚少。我们调查有和没有CLBP的个体在动态等速运动性疲劳任务期间肌肉激活和峰值扭矩施加的区域变化。

方法

肌电图（EMG）使用高密度肌电图（13×5电极网格）单侧从11个无症状对照和12个CLBP个体的腰直肌中获取。参与者坐在等速测功机上，以60 ^o / s的速度连续进行躯干连续屈伸运动，直至身体疲劳。

发现

两组的肌肉激活水平和重复次数相似（p  > 0.05）。但是，CLBP组在屈曲和伸展力矩上均表现出较低的峰值扭矩水平（p  <0.05）。在整个任务中，CLBP组的腰直肌脊柱活动中心发生了颅骨移位（p  <0.05），而对照组参与者的肌肉活动分布更均匀。

解释

患有CLBP的人在动态疲劳训练任务期间显示出其腰直肌脊椎的激活改变且可能效率较低。未来的研究应考虑使用高密度肌电生物反馈来优化腰背痛（LBP）患者椎旁肌肉的空间激活。