Which of the following decreases in length during the contraction of a skeletal muscle fiber?
The physical lengths of the actin and myosin filaments do not change during contraction. Therefore, the A band, which is composed of myosin filaments, does not change either. The distance between Z disks decreases, but the Z disks themselves do not change. Only the I band decreases in length as the muscle contracts.
A band of the sarcomere
I band of the sarcomere
Thick filaments
Thin filaments
Muscle