Stretch forces in skeletal muscle myofibrils and myosin molecules

肌肉收缩是生命的基本功能。用于解释肌肉收缩机制的标准理论被称为跨桥理论，它是在半个世纪前提出的。然而，肌肉收缩的几个方面仍然知之甚少。在这些方面中，激活的肌肉纤维在拉伸过程中产生的高力不能很容易地用跨桥理论来解释。这项建议的目标是研究牵伸力背后的机制，以及它与肌肉收缩的分子基础之间的联系。我们建议使用新的和准确的测量方法，包括单肌纤维(肌肉纤维的亚细胞成分)和单分子力学来测试已经提出的解释拉力的假说。这些假说与收缩过程中肌肉纤维内的收缩蛋白和被动元素的作用有关。牵伸力不仅对了解收缩的基本机制很重要，而且对日常生活的几个方面也很重要，如拉伸引起的肌肉损伤，以及在偏心收缩时的力量增强。

Muscle contraction is a basic function of life. The standard theory used to explain the mechanisms of muscle contraction is known as the cross-bridge theory, and was proposed half a century ago. However, several aspects of muscle contraction are still poorly understood. Among these aspects, the high forces produced during stretch of an activated muscle fiber cannot be readily explained by the cross-bridge theory. The goal of this proposal is to investigate the mechanisms behind stretch forces, and its association with the molecular basis of muscle contraction. We propose to use novel and accurate methods of measurement that include single myofibrils (sub-cellular components of muscle fibers) and single molecule mechanics to test hypotheses that have been raised to explain stretch forces. These hypotheses are associated with the role of contractile proteins and passive elements inside muscle fibers during contraction. Stretch forces are important not only to understand the basic mechanisms of contraction, but also several aspects of the everyday life, like stretch-induced muscle damage, and force potentiation during eccentric contractions.