The myofiber is the smallest complete contractile system. As such, it requires subsystems for metabolism, excitation and contraction. Metabolism Metabolism in muscle cells is much like metabolism in any cell. Nutrients are brought into the cell and oxidized to release energy. The most common examples of this are glycolysis and fatty acid breakdown.
Muscles make use of other energy intermediaries , as well.
Excitation For effective force production, contraction must be excited along the whole length of a fiber simultaneously. Contraction Within each myofiber are a network of myofibrils . These fibrils contain the proteins that do the actual force production. It is because of these fibrils that skeletal muscle demonstrates its characteristic striated pattern. An extensive network of proteins binds each myofibril to its neighboring fibril and to the cell membrane.