Department of Biomedical Engineering, Nanchang Hangkong University, Jiangxi, China.
Department of Biomedical Engineering, Nanchang Hangkong University, Jiangxi, China.
Brain Res. 2025 Jan 1;1846:149244. doi: 10.1016/j.brainres.2024.149244. Epub 2024 Sep 16.
Postural control imposes higher demands on the central neural system (CNS), and age-related declines or incomplete CNS development often result in challenges performing tasks like forward postural leaning. Studies on older adults suggest increased variability in center of pressure (COP), greater muscle co-activations, and reduced corticospinal control during forward leaning tasks. However, the understanding of these features in children remains unclear. Specifically, it is uncertain whether forward leaning poses greater challenges for young children compared to adults, given the ongoing maturation of CNS during development. Understanding the distinct neuromuscular patterns observed during postural leaning could help optimize therapeutic strategies aimed at improving postural control in pediatric populations.
12 typically developing children (5.91 ± 1.37 years) and 12 healthy young adults (23.16 ± 1.52 years) participated in a dynamic leaning forward task aimed at matching a COP target in the anterior-posterior direction as steadily as possible. Participants traced a triangular trajectory involving forward leaning (FW phase) to 60 % of their maximum lean distance and backward returning (BW phase) to the neutral standing position. Surface electromyography (sEMG) from muscles including gastrocnemius medialis (GM), soleus (SOL), and tibialis anterior (TA) were collected during both phases. COP variability was assessed using the standard deviation (SD) of COP displacements. Muscle co-activation indexes (CI) for ankle plantar and dorsal flexors (SOL/TA, GM/TA) were derived from sEMG activities. Intermuscular coherence in the beta band (15-30 Hz) was also analyzed to evaluate corticospinal drive.
Children exhibited a significantly greater SD of COP compared to young adults (p < 0.01) during the BW phase. They also demonstrated higher CI (p < 0.05) and reduced coherence of SOL/TA (p < 0.05) compared to young adults during this phase. No significant group differences were observed during the FW phase. Within the children's group, COP variability was significantly higher in the BW phase compared to the FW phase (p < 0.01). Moreover, children displayed greater CI (p < 0.01) and reduced coherence of SOL/TA (p < 0.01) during the BW phase compared to the FW phase. Conversely, no significant phase effects were observed in the adult group. Furthermore, sEMG measures were significantly correlated with COP variability (p < 0.05).
The findings of this small study suggest that age-related differences in CNS development influence the modulation of corticospinal drive to ankle muscles (e.g., SOL/TA) during childhood, particularly supporting the existence of a separate pathway underlying the control of forward lean and backward returning.
姿势控制对中枢神经系统（CNS）提出了更高的要求，而年龄相关的衰退或 CNS 发育不完全通常会导致在进行前倾姿势等任务时出现挑战。针对老年人的研究表明，在前倾任务中，压力中心（COP）的变异性增加，肌肉协同收缩增加，皮质脊髓控制减少。然而，儿童的这些特征仍不清楚。具体来说，鉴于 CNS 在发育过程中的持续成熟，尚不确定前倾对儿童的挑战是否大于成年人。了解在姿势前倾过程中观察到的独特神经肌肉模式，有助于优化针对儿科人群的姿势控制的治疗策略。
12 名发育正常的儿童（5.91±1.37 岁）和 12 名健康的年轻成年人（23.16±1.52 岁）参与了一项旨在尽可能稳定地追踪前-后向 COP 目标的动态前倾任务。参与者在 FW 阶段（前倾阶段）前倾至最大倾斜距离的 60%，然后在 BW 阶段（后倾阶段）返回到中立站立位置。在这两个阶段，从包括内侧腓肠肌（GM）、比目鱼肌（SOL）和胫骨前肌（TA）在内的肌肉中采集表面肌电图（sEMG）。使用 COP 位移的标准差（SD）评估 COP 变异性。从 sEMG 活动中得出踝部跖屈和背屈肌（SOL/TA、GM/TA）的肌肉协同收缩指数（CI）。还分析了β频段（15-30 Hz）的肌间相干性，以评估皮质脊髓驱动。
与年轻成年人相比，儿童在 BW 阶段的 COP SD 显著更大（p<0.01）。与年轻成年人相比，他们在 BW 阶段还表现出更高的 CI（p<0.05）和 SOL/TA 的相干性降低（p<0.05）。在 FW 阶段，两组之间没有观察到显著的组间差异。在儿童组内，BW 阶段的 COP 变异性显著高于 FW 阶段（p<0.01）。此外，与 FW 阶段相比，BW 阶段儿童的 CI（p<0.01）和 SOL/TA 的相干性降低（p<0.01）。相比之下，成人组没有观察到显著的相位效应。此外，sEMG 测量值与 COP 变异性显著相关（p<0.05）。
这项小型研究的结果表明，CNS 发育的年龄相关差异会影响儿童时期对皮质脊髓驱动到踝部肌肉（例如，SOL/TA）的调节，这尤其支持在控制前倾和后倾的过程中存在独立的途径。
