Department of Biomechanics in Sports, Leipzig University, Leipzig, Germany.
Department for Orthopedics, Trauma and Plastic Surgery, Leipzig University, Leipzig, Germany.
PLoS One. 2023 Dec 19;18(12):e0293439. doi: 10.1371/journal.pone.0293439. eCollection 2023.
Strengthening the rotator cuff muscles is important for injury prevention and rehabilitation. Since muscle fascicle length improves motor performance and is suggested to reduce the risk of injury for the hamstring, it may be an important variable to promote multidirectional changes in the function and macroscopic structure for the shoulder. Recent literature reviews overwhelmingly suggest that eccentric exercises improve fascicle length and functional measures for the lower limb. However, there is a research gap for the shoulder. Since ultrasound imaging is the most commonly used imaging technique to quantify muscle structure, but has yielded heterogeneous results in different studies, there is another issue and a research gap for the imaging method. Based on the research gaps, the purpose of this study was to evaluate the effects of standardized eccentric strength training on the function and structure of the external rotator cuff muscles using an isokinetic dynamometer and MRI. Therefore, a preliminary pre-post intervention study was conducted and 16 physically active men were recruited in October 2021. For the right shoulder, an eccentric isokinetic training was performed twice a week for almost six weeks. The primary outcome measures (external rotators) were active and passive range of motion, eccentric and concentric torque at 30, 60, and 180°/s isokinetic speed, and fascicle length and fascicle volume for the supraspinatus and infraspinatus muscles. The findings show a training effect for the absolute mean values of eccentric strength (+24%, p = .008). The torque-angle relationship increased, especially in the final phase of range of motion, although a 4% (p = .002) decrease in passive range of motion was found in the stretch test. Positive changes in muscle structure were shown for the supraspinatus muscle fascicle length (+16%, p = .003) and fascicle volume (+19%, p = .002). Based on the study results, we can conclude that eccentric isokinetic training has a significant positive effect on the shoulder. To our knowledge, this is the first eccentric training study using both isokinetic dynamometer and muscle diffusion tensor imaging to access functional and structural changes in the human shoulder rotator cuff muscles. The methods were shown to be applicable for interventional studies. Based on these results, populations such as high-performance handball players with highly trained shoulders should be included in future studies.
加强肩袖肌肉对于预防和康复损伤很重要。由于肌束长度可以改善运动表现，并被认为可以降低腘绳肌受伤的风险，因此它可能是促进肩部功能和宏观结构多方向变化的重要变量。最近的文献综述强烈表明，离心运动可以改善下肢的肌束长度和功能测量值。但是，肩部的研究还存在空白。由于超声成像技术是最常用于量化肌肉结构的成像技术，但在不同的研究中产生了不一致的结果，因此成像方法也存在另一个问题和研究空白。基于这些研究空白，本研究旨在使用等速测力仪和 MRI 评估标准化离心力量训练对外部旋转袖肌肉功能和结构的影响。因此，进行了一项初步的干预前后研究，于 2021 年 10 月招募了 16 名活跃的男性。对于右肩，每周进行两次离心等速训练，持续近六周。主要的结局测量指标（外部旋转肌）为主动和被动运动范围、30、60 和 180°/s 等速速度下的离心和向心扭矩，以及冈上肌和冈下肌的肌束长度和肌束体积。研究结果显示，离心力量的绝对值平均增加了 24%（p =.008）。在运动范围的最后阶段，扭矩-角度关系增加，尽管在伸展测试中发现被动运动范围减少了 4%（p =.002）。冈上肌肌束长度（增加 16%，p =.003）和肌束体积（增加 19%，p =.002）均显示出积极的肌肉结构变化。基于研究结果，我们可以得出结论，离心等速训练对肩部有显著的积极影响。据我们所知，这是第一项使用等速测力仪和肌肉扩散张量成像来评估人类肩部旋转袖肌肉功能和结构变化的离心训练研究。这些方法已被证明适用于干预性研究。基于这些结果，未来的研究应该包括高表现的手球运动员等肩部训练高度发达的人群。
