Chair of Solid Mechanics, School of Mechanical and Safety Engineering, University of Wuppertal, Germany.
Chair of Solid Mechanics, School of Mechanical and Safety Engineering, University of Wuppertal, Germany; Wuppertal Center for Smart Materials, University of Wuppertal, Germany.
J Mech Behav Biomed Mater. 2022 Oct;134:105386. doi: 10.1016/j.jmbbm.2022.105386. Epub 2022 Jul 27.
One of the skeletal muscle's exceptional properties is its high damage tolerance in terms of its high toughness, which allows the muscle to withstand cracks of millimeter length while maintaining most of its strength (Taylor et al., 2012). In skeletal muscles, damage occurs on different hierarchical levels of the microstructure. We analyze the damage behavior on hierarchy levels 3 (muscle fiber) and 4 (fascicle) on which the most common serious muscle injuries occur. Our model captures damage initiation and rupture of activated muscle fibers resulting from eccentric contractions. We consider the interaction between muscle fibers and endomysium and investigate the influence of the components titin and endomysium on the mechanical behavior in pre-damaged fascicles. Endomysium generally transmits contractile forces. Our results show that high strains in pre-damaged fiber regions are not transferred by the endomysium and, thus, adjacent undamaged fibers are well protected. Moreover, the results show titin's extraordinary stabilization properties of pre-damaged muscle fibers, so that macroscopic strains of fascicles are hardly reduced in case of strongly pre-damaged fibers and intact titin.
骨骼肌的一个显著特性是其具有很高的韧性，这意味着它具有很高的损伤容限，能够在保持大部分强度的情况下承受毫米级的裂纹（Taylor 等人，2012 年）。在骨骼肌中，损伤发生在微观结构的不同层次上。我们分析了在层次 3（肌纤维）和层次 4（肌束）上的损伤行为，这两个层次是最常见的严重肌肉损伤发生的层次。我们的模型捕捉了由于离心收缩而导致的激活肌纤维的损伤起始和破裂。我们考虑了肌纤维和肌内膜之间的相互作用，并研究了肌联蛋白和肌内膜对预损伤肌束机械行为的影响。肌内膜通常传递收缩力。我们的结果表明，预损伤纤维区域的高应变不会被肌内膜传递，因此相邻的未损伤纤维得到了很好的保护。此外，结果还表明肌联蛋白对预损伤肌纤维具有非凡的稳定特性，因此在纤维严重预损伤且肌联蛋白完整的情况下，肌束的宏观应变几乎不会减小。
