Sheikhhoseini Rahman, Abdollahi Sajjad, Salsali Mohammad, Anbarian Mehrdad
Department of Corrective Exercise & Sport Injury, Faculty of Physical Education and Sport Sciences, Allameh Tabataba'i University, Tehran, Iran.
Faculty of Sport Sciences, Allameh Tabataba'i University, Western Azadi Sport Complex Boulevard, Hakim Highway, Tehran, Iran.
Sci Rep. 2025 Jan 3;15(1):718. doi: 10.1038/s41598-025-85226-5.
Most sports and leisure activities involve repetitive movements in the upper limb, which are typically linked to pain and discomfort in the neck and shoulder area. Movement variability is generally expressed by changes in movement parameters from one movement to another and is a time-dependent feature of repetitive activities. The purpose of this study was to examine the effect of repeated movement-induced fatigue on biomechanical coordination and variability in athletes with and without chronic shoulder pain (CSP). In this controlled laboratory study, 24 overhead athletes in two groups of athletes with (N = 12) and without (N = 12) CSP were recruited. Biomechanical and Electromyographical data were recorded while the athletes were asked to perform repeating reaching tasks (RRT). Kinematic data was recorded every 30 s of the minutes of the repetitive pointing task (RPT). The kinematic and electromyography data were recorded at the first 30 s of "Fatigue-Terminal" (FT) and the last 30 s of "No-Fatigue" (NF) in the repetitive pointing task (RPT). Raw data was analyzed by using MATLAB code to extract the relevant coordination and movement variability data. Different fatigue conditions led to significant kinematic changes during the repetitive pointing task. In the CSP group, trunk lateral flexion decreased after fatigue, while it increased in the CON group (p < 0.013). Trunk rotation and shoulder elevation angles were smaller before fatigue than after in both groups (p < 0.001). Variability in joint angles, including trunk lateral flexion and elbow flexion, increased after fatigue, indicating less stability in movement patterns (p < 0.001). The coordination between trunk movement and shoulder elevation was altered post-fatigue, with significant changes in EMG variability for muscles like the Lower Trapezius and Long Head of the Biceps (p < 0.001). Results of our study indicate that both groups were able to accomplish fatigue, but they employed different movement strategies. The CSP group primarily focused on controlling the shoulder joint, while the CON group utilized both the shoulder and elbow joints in their strategy. This difference suggests that individuals in the CSP group who experienced chronic pain may have developed a strategy to minimize pain and fatigue during the task. Specifically, the CSP group's approach appeared to involve adjustments in movement patterns to manage the task despite fatigue. This adaptation contrasts with the CON group's more complex movement strategy, which involved greater variability and adjustments in both the shoulder and elbow joints.
大多数体育和休闲活动都涉及上肢的重复性动作，这些动作通常与颈部和肩部区域的疼痛和不适有关。运动变异性通常通过从一个动作到另一个动作的运动参数变化来表示，并且是重复性活动的一个与时间相关的特征。本研究的目的是检查重复运动诱发的疲劳对患有和未患有慢性肩部疼痛（CSP）的运动员的生物力学协调性和变异性的影响。在这项对照实验室研究中，招募了两组24名从事过头运动的运动员，一组患有CSP（N = 12），另一组未患有CSP（N = 12）。在运动员执行重复伸手任务（RRT）时记录生物力学和肌电图数据。在重复性指向任务（RPT）的每分钟的第30秒记录运动学数据。在重复性指向任务（RPT）的“疲劳末期”（FT）的前30秒和“无疲劳”（NF）的最后30秒记录运动学和肌电图数据。使用MATLAB代码分析原始数据，以提取相关的协调性和运动变异性数据。不同的疲劳条件导致重复性指向任务期间运动学有显著变化。在CSP组中，疲劳后躯干侧屈减少，而在对照组中则增加（p < 0.013）。两组在疲劳前的躯干旋转和肩部抬高角度均小于疲劳后（p < 0.001）。包括躯干侧屈和肘部屈曲在内的关节角度变异性在疲劳后增加，表明运动模式的稳定性降低（p < 0.001）。疲劳后躯干运动与肩部抬高之间的协调性发生改变，斜方肌下肌和肱二头肌长头等肌肉的肌电图变异性有显著变化（p < 0.001）。我们的研究结果表明，两组都能够完成疲劳，但他们采用了不同的运动策略。CSP组主要专注于控制肩关节，而对照组在其策略中同时利用了肩关节和肘关节。这种差异表明，经历慢性疼痛的CSP组个体可能已经制定了一种策略，以在任务期间将疼痛和疲劳降至最低。具体而言，CSP组的方法似乎涉及调整运动模式以在疲劳状态下完成任务。这种适应性与对照组更复杂的运动策略形成对比，对照组的策略涉及肩关节和肘关节更大的变异性和调整。
