Romero Avila Elisa, Disselhorst-Klug Catherine
Department of Rehabilitation and Prevention Engineering, Institute of Applied Medical Engineering, RWTH Aachen University, Pauwelsstr. 20, 52074, Aachen, Germany.
Eur J Appl Physiol. 2025 Apr 26. doi: 10.1007/s00421-025-05791-5.
This work analyzes how the Central Nervous System (CNS) adapts its control strategies-muscle synergies and muscular coactivation-during unfamiliar elbow flexion/extension tasks at different velocities.
Twenty healthy participants (10 male; 10 female; age 31 ± 10,2 years) were recruited. Muscular activation of the biceps brachii, brachioradialis, and triceps brachii was recorded using surface electromyography. Elbow movements were tracked using a motion-capture system and an upper body biomechanical model. To represent an unfamiliar task, participants performed the movement in the transverse plane, while the familiar task was performed in the sagittal plane to allow for comparison. Movements were executed at different angular velocities to assess their effect. Muscle synergies were identified using the Non-Negative Matrix Factorization method.
The results indicate that the CNS adapts to unfamiliar movements primarily by increasing muscular coactivation to control position and movement velocity (p < 0.001, comparing familiar versus unfamiliar tasks). In contrast, during familiar tasks, the CNS achieves the stability required for faster movements through a higher contribution of muscle synergies (p < 0.05, comparing slowest versus fastest velocity). The statistical results revealed no significant interaction between task familiarity and movement velocity, suggesting that the effect of task familiarity on muscular activation remains consistent across all angular velocities.
This work provides valuable insights into how muscle synergies and muscular coactivation complement each other. For an unfamiliar elbow flexion/extension task, the CNS primarily adapts by increasing the activation of all muscles acting on the joint to control position and movement velocity.
本研究分析中枢神经系统（CNS）在不同速度下进行不熟悉的肘部屈伸任务时，如何调整其控制策略——肌肉协同作用和肌肉共同激活。
招募了20名健康参与者（10名男性；10名女性；年龄31±10.2岁）。使用表面肌电图记录肱二头肌、肱桡肌和肱三头肌的肌肉激活情况。使用运动捕捉系统和上身生物力学模型跟踪肘部运动。为了呈现不熟悉的任务，参与者在横断面进行运动，而熟悉的任务在矢状面进行以便比较。以不同角速度执行运动以评估其效果。使用非负矩阵分解方法识别肌肉协同作用。
结果表明，中枢神经系统适应不熟悉运动主要是通过增加肌肉共同激活来控制位置和运动速度（p<0.001，比较熟悉与不熟悉任务）。相比之下，在熟悉的任务中，中枢神经系统通过肌肉协同作用的更高贡献实现更快运动所需的稳定性（p<0.05，比较最慢与最快速度）。统计结果显示任务熟悉度和运动速度之间无显著交互作用，表明任务熟悉度对肌肉激活的影响在所有角速度下均保持一致。
本研究为肌肉协同作用和肌肉共同激活如何相互补充提供了有价值的见解。对于不熟悉的肘部屈伸任务，中枢神经系统主要通过增加作用于关节的所有肌肉的激活来控制位置和运动速度。
