In this study, we tested the hypotheses that unaccustomed eccentric exercise (ECC) would reduce the elastic modulus and dynamic stiffness of the upper trapezius muscle and that these changes would correlate with increases in muscle thickness, reflecting muscle edema. Shear wave elastography was used to measure elastic modulus, dynamic stiffness was assessed using myotonometry, and muscle thickness was measured using ultrasonography. All measurements were performed at four locations over the upper trapezius before and 24 h after a single bout of ECC. Fourteen healthy participants (11 males and 3 females; 23.2 ± 3.0 years; height 175.1 ± 10.4 cm; body mass 73.8 ± 11.3 kg) took part in the study. Overall, ECC resulted in decreased elastic modulus (from 45.8 ± 1.6 to 39.4 ± 1.2 kPa, p < 0.01) and dynamic muscle stiffness (from 369.0 ± 7.3 to 302.6 ± 6.0 N/m, p < 0.01). Additionally, ECC resulted in increased muscle thickness (from 6.9 ± 0.4 to 7.3 ± 0.4 mm, p < 0.01). Spatial changes (across the four locations) were found for elastic modulus, stiffness and thickness. No significant correlations were found between changes in measures of muscle stiffness, or between changes in stiffness and changes in thickness. In conclusion, the present pilot study showed that ECC altered biomechanical muscle properties, reflected by decreased elastic modulus and dynamic muscle stiffness 24 h after ECC.

中文翻译：

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通过剪切波弹性成像和肌张力测定法评估的离心运动降低上斜方肌的刚度

在这项研究中，我们测试了以下假设：不习惯的离心运动 (ECC) 会降低上斜方肌的弹性模量和动态刚度，并且这些变化与肌肉厚度的增加相关，反映肌肉水肿。剪切波弹性成像用于测量弹性模量，使用肌张力测量法评估动态刚度，并使用超声检查测量肌肉厚度。所有测量均在单次 ECC 之前和之后 24 小时在斜方肌上部的四个位置进行。14 名健康参与者（11 名男性和 3 名女性；23.2 ± 3.0 岁；身高 175.1 ± 10.4 厘米；体重 73.8 ± 11.3 公斤）参加了这项研究。总体而言，ECC 导致弹性模量降低（从 45.8 ± 1.6 到 39.4 ± 1.2 kPa，p < 0.01）和动态肌肉僵硬（从 369.0 ± 7.3 到 302。6 ± 6.0 N/m，p​​ < 0.01)。此外，ECC 导致肌肉厚度增加（从 6.9 ± 0.4 到 7.3 ± 0.4 mm，p < 0.01）。发现弹性模量、刚度和厚度的空间变化（跨越四个位置）。未发现肌肉硬度测量值变化之间或硬度变化与厚度变化之间存在显着相关性。总之，目前的初步研究表明，ECC 改变了生物力学肌肉特性，反映在 ECC 后 24 小时弹性模量和动态肌肉刚度降低。未发现肌肉硬度测量值变化之间或硬度变化与厚度变化之间存在显着相关性。总之，目前的初步研究表明，ECC 改变了生物力学肌肉特性，反映在 ECC 后 24 小时弹性模量和动态肌肉刚度降低。没有发现肌肉僵硬测量值变化之间或僵硬变化与厚度变化之间的显着相关性。总之，目前的初步研究表明，ECC 改变了生物力学肌肉特性，反映在 ECC 后 24 小时弹性模量和动态肌肉刚度降低。