All muscle cells are specialized for contraction. When these cells contract, they shorten and pull a bone to produce movement. Each skeletal muscle is made of thousands of individual muscle cells, which also may be called muscle fibers . Depending on the work a muscle is required to do, variable numbers of muscle fibers contract. […]

The final common determinant of success in athletic events is what the muscles can do for you—what strength they can give when it is needed, what power they can achieve in the performance of work, and how long they can continue their activity.
The strength of a muscle is determined mainly by its size, with a […]