This study aims to identify how spatial distribution of lumbar muscle activity is modulated by different fatigue tasks. Twenty healthy adults performed two different isometric trunk extension endurance tasks (the modified Sorensen test and the inverted modified Sorensen test) until exhaustion. During these tasks, bilateral superficial lumbar muscle activity was recorded using high-density electromyography. The spatial distribution of activation within these muscles was obtained using the centroid coordinates in the medio-lateral and cranio-caudal directions. The effects of task and endurance time (left and right sides) were investigated using repeated measures ANOVA. Results revealed a significant lateral shift of the centroid throughout the fatigue tasks on both sides and no difference between tasks. Significant task × time interaction effects were found for the cranio-caudal direction on both sides showing a significantly more caudal location of the centroid in the modified Sorensen test compared to the inverted test at the beginning of the tasks. Our findings suggest that spatial distribution of lumbar muscle activity is task-dependent in a pre-fatigue stage while an alternative but similar muscle recruitment strategy is used in both tasks to maintain performance in the later stages of muscle fatigue.

本研究旨在确定不同疲劳任务如何调节腰部肌肉活动的空间分布。二十名健康成年人执行两种不同的等长躯干伸展耐力任务（改良索伦森测试和倒置改良索伦森测试）直到精疲力尽。在这些任务期间，使用高密度肌电图记录双侧浅表腰肌活动。使用中外侧和颅尾方向的质心坐标获得这些肌肉内激活的空间分布。使用重复测量方差分析研究任务和耐力时间（左侧和右侧）的影响。结果显示，在两侧的疲劳任务中，质心都有显着的横向移动，并且任务之间没有差异。在两侧的头尾方向上发现了显着的任务×时间交互效应，表明与任务开始时的倒置测试相比，修改后的索伦森测试中质心的位置明显更靠尾。我们的研究结果表明，腰部肌肉活动的空间分布在疲劳前阶段是依赖于任务的，而在这两项任务中都使用了替代但相似的肌肉募集策略，以维持肌肉疲劳后期的表现。