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

半个多世纪前，A·赫胥黎提出了肌肉收缩的跨桥理论，这一理论在目前的解剖学和生理学教科书中得到了体现。根据跨桥理论，肌肉缩短是通过肌动蛋白和肌球蛋白两组细丝的相对滑动发生的。这种滑动是由从肌球蛋白细丝伸出的横桥产生的，它周期性地附着在肌动蛋白上，并将肌动蛋白拉过肌球蛋白细丝。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，用这一理论无法预测肌肉收缩的基本特性。在过去的十年里，我们研究了这些无法解释的属性，得出的结论是，肌肉力量产生的两个细丝思维需要修改，第三个细丝--分子弹簧titin--需要添加到我们对肌肉收缩和力量产生的思维中。

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.