MUSCLE PHYSIOLOGY

Detailed explanation-1: -During muscle contraction, the I band is reduced in size as the overlap between the thick and thin filaments increases. The Z-lines come together, and so the sarcomere shortens as well.

Detailed explanation-2: -The molecular events of muscle fiber shortening occur within the fiber’s sarcomeres (see [link]). The contraction of a striated muscle fiber occurs as the sarcomeres, linearly arranged within myofibrils, shorten as myosin heads pull on the actin filaments.