Can Sarcomere Change Length?

Sarcomeres are highly stereotyped and are repeated throughout muscle cells, and the proteins within them can change in length, which causes the overall length of a muscle to change. An individual sarcomere contains many parallel actin (thin) and myosin (thick) filaments.

Does the sarcomere shorten?

Sliding filament model of contraction. For a muscle cell to contract, the sarcomere must shorten. However, thick and thin filaments—the components of sarcomeres—do not shorten. Instead, they slide by one another, causing the sarcomere to shorten while the filaments remain the same length.

What causes the sarcomere to shorten during a contraction?

B: With contraction, movement of the thin filaments toward the center of the sarcomere occurs, and because the thin filaments are anchored to the Z disks, their movement causes shortening of the sarcomere.