Abstract：
Muscles are affected at the cellular level by exercised-induced fatigue, inducing changes in their stiffness. Examining muscle stiffness can improve the knowledge of various pathologic conditions, such as pain and injury. The objective of this study was to examine the stiffness of the medial gastrocnemius (MG) muscle and the lateral gastrocnemius (LG) muscle to determine the changes in stiffness, and to assess the differences in the stiffness between the MG and the LG, as affected by muscle fatigue measured using shear wave elastography (SWE) and a MyotonPRO after inducing muscle fatigue. A total of 35 healthy young adults participated in the study. The stiffness of the MG and the LG were assessed before and after a muscle fatigue protocol (MFP), which included three sets of 50 eccentric contractions of the calf muscles of the dominant leg, at rest, and at maximum voluntary contraction (MVC). The measurements were taken with SWE and the MyotonPRO simultaneously. Compared to baseline, the resting stiffness of the MG and the LG significantly increased immediately, 24 h, and 48 h after muscle fatigue (p < 0.05); however, during MVC, the stiffness of the MG decreased (p < 0.05) and that of the LG showed no change (p > 0.05). When the stiffness of the MG and the LG were compared before and after the MFP, changes in the stiffness of the MG were significantly greater than those in the LG (p < 0.05). This signifies that the MG was more affected by the exercise-induced muscle fatigue than was the LG. The assessment of musculoskeletal tissue and its characteristics, before and after eccentric exercise, is crucial in the prevention of overuse injuries associated with repeated exposure to both low and high levels of force.
摘要：
肌肉在细胞水平受到运动引起的疲劳的影响，诱导其刚度的变化。检查肌肉僵硬度可以提高对各种病理状况的认识，如疼痛和伤害。这项研究的目的是检查内侧腓肠肌（MG）肌肉和外侧腓肠肌（LG）肌肉的刚度，以确定刚度的变化，并评估MG和LG之间的刚度差异，受诱导肌肉疲劳后使用剪切波弹性成像（SWE）和MyotonPRO测量的肌肉疲劳的影响。共有35名健康的年轻人参加了这项研究。在肌肉疲劳方案（MFP）之前和之后评估MG和LG的刚度，其中包括优势腿小腿肌肉的三组50次偏心收缩，在休息时,和最大自愿收缩(MVC)。用SWE和MyotonPRO同时进行测量。与基线相比，MG和LG的静息刚度立即显着增加，24h,和肌肉疲劳后48小时(p<0.05)；然而，在MVC期间，MG的刚度降低（p<0.05），LG的刚度没有变化（p>0.05）。当MG和LG的刚度在MFP之前和之后进行比较时，MG的刚度变化显着大于LG（p<0.05）。这表明MG比LG更受运动引起的肌肉疲劳的影响。肌肉骨骼组织的评估及其特征，偏心运动前后，对于预防与反复暴露于低和高水平力量相关的过度使用伤害至关重要。
