function to muscle cells. The weakened contractile function of skeletal muscle is also linked to the state of the myofibrils. Recent studies suggest that these conditions are associated with altered single fiber performance due to decreased expression of myofilament proteins and/or changes in myosin-actin cross-bridge interactions. Furthermore, cellular and myofilament-level adaptations are related to diminished whole muscle and whole body performance. References Muscle :: Diversity of Muscle—Britannica Online Encyclopedia." Encyclopedia - Britannica Online Encyclopedia. Web. Saladin, Kenneth S. "Myofilaments." Anatomy & Physiology: the Unity of Form and Function. 5th ed. New York: McGraw-Hill, 2010. 406–07. Print. External links Diagrams and explanations at biomol.uci.edu Cell movement