Abboud Jacques, Nougarou François, Lardon Arnaud, Dugas Claude, Descarreaux Martin
Département d'Anatomie, Université du Québec à Trois-Rivières Trois-Rivières, QC, Canada.
Département de Génie Électrique, Université du Québec à Trois-Rivières Trois-Rivières, QC, Canada.
Front Hum Neurosci. 2016 Nov 14;10:576. doi: 10.3389/fnhum.2016.00576. eCollection 2016.
: When the spine is subjected to perturbations, neuromuscular responses such as reflex muscle contractions contribute to the overall balance control and spinal stabilization mechanisms. These responses are influenced by muscle fatigue, which has been shown to trigger changes in muscle recruitment patterns. Neuromuscular adaptations, e.g., attenuation of reflex activation and/or postural oscillations following repeated unexpected external perturbations, have also been described. However, the characterization of these adaptations still remains unclear. Using high-density electromyography (EMG) may help understand how the nervous system chooses to deal with an unknown perturbation in different physiological and/or mechanical perturbation environments. : To characterize trunk neuromuscular adaptations following repeated sudden external perturbations after a back muscle fatigue task using high-density EMG. : Twenty-five healthy participants experienced a series of 15 sudden external perturbations before and after back muscle fatigue. Erector spinae muscle activity was recorded using high-density EMG. Trunk kinematics during perturbation trials were collected using a 3-D motion analysis system. A two-way repeated measure ANOVA was conducted to assess: (1) the adaptation effect across trials; (2) the fatigue effect; and (3) the interaction effect (fatigue × adaptation) for the baseline activity, the reflex latency, the reflex peak and trunk kinematic variables (flexion angle, velocity and time to peak velocity). Muscle activity spatial distribution before and following the fatigue task was also compared using -tests for dependent samples. : An attenuation of muscle reflex peak was observed across perturbation trials before the fatigue task, but not after. The spatial distribution of muscle activity was significantly higher before the fatigue task compared to post-fatigue trials. Baseline activity showed a trend to higher values after muscle fatigue, as well as reduction through perturbation trials. Main effects of fatigue and adaptation were found for time to peak velocity. No adaptation nor fatigue effect were identified for reflex latency, flexion angle or trunk velocity. : The results show that muscle fatigue leads to reduced spatial distribution of back muscle activity and suggest a limited ability to use across-trial redundancy to adapt EMG reflex peak and optimize spinal stabilization using retroactive control.
当脊柱受到干扰时，神经肌肉反应（如反射性肌肉收缩）有助于整体平衡控制和脊柱稳定机制。这些反应会受到肌肉疲劳的影响，研究表明肌肉疲劳会引发肌肉募集模式的变化。神经肌肉适应性，例如在反复意外外部干扰后反射激活和/或姿势振荡的减弱，也有相关描述。然而，这些适应性的特征仍不清楚。使用高密度肌电图（EMG）可能有助于理解神经系统在不同生理和/或机械干扰环境中如何选择应对未知干扰。
使用高密度肌电图来表征背部肌肉疲劳任务后反复突然外部干扰后的躯干神经肌肉适应性。
25名健康参与者在背部肌肉疲劳前后经历了一系列15次突然外部干扰。使用高密度肌电图记录竖脊肌活动。在干扰试验期间，使用三维运动分析系统收集躯干运动学数据。进行双向重复测量方差分析以评估：（1）各试验间的适应效果；（2）疲劳效果；（3）基线活动、反射潜伏期、反射峰值和躯干运动学变量（屈曲角度、速度和达到峰值速度的时间）的交互作用（疲劳×适应）。还使用配对样本t检验比较了疲劳任务前后肌肉活动的空间分布。
在疲劳任务前的各干扰试验中观察到肌肉反射峰值减弱，但疲劳任务后未观察到。与疲劳后试验相比，疲劳任务前肌肉活动的空间分布明显更高。基线活动在肌肉疲劳后有升高趋势，并且在干扰试验中降低。对于达到峰值速度，发现了疲劳和适应的主要影响。对于反射潜伏期、屈曲角度或躯干速度，未发现适应或疲劳效应。
结果表明肌肉疲劳会导致背部肌肉活动的空间分布减少，并表明利用试验间冗余来适应肌电图反射峰值和通过追溯控制优化脊柱稳定的能力有限。
