Force-sharing among synergistic muscles and mechanical properites of skeletal muscles

半个多世纪前，A.赫胥黎发展了肌肉收缩的跨桥理论，这一理论在当前的解剖学和生理学教科书中有代表性。根据跨桥理论，肌肉缩短是通过两组细丝（肌动蛋白和肌球蛋白）的相对滑动发生的。这种滑动是由从肌球蛋白丝突出的横桥产生的，横桥周期性地附着在肌动蛋白上，并将肌动蛋白拉过肌球蛋白丝。虽然这一理论有助于我们理解肌肉是如何工作的，但从一开始就知道，肌肉收缩的基本特性无法用这一理论来预测。在过去的十年里，我们研究了这些“无法解释的”性质，并得出结论，认为肌肉力量产生的两条细丝需要修改，第三条细丝，分子弹簧肌联蛋白，需要加入我们对肌肉收缩和力量产生的思考。

More than half a century ago, A. Huxley developed the cross-bridge theory of muscle contraction, a theory that is represented in current textbooks of anatomy and physiology. According to the cross-bridge theory, muscle shortening occurs through the relative sliding of two sets of filaments, actin and myosin. This sliding is produced by cross-bridges that protrude from the myosin filament, attach cyclically to actin, and pull actin past the myosin filament. Although this theory has served our understanding of how muscles work well, it was known from the very beginning that basic properties of muscle contraction could not be predicted with this theory. Over the past ten years, we have studied these "unexplained" properties and concluded that the two filament thinking of muscle force production needs revision, and that a third filament, the molecular spring titin, needs to be added to our thinking of muscle contraction and force production.