Answer:
True.
Step-by-step explanation:
The sliding filament model states that, during muscular contraction, each sarcomere is shrunk, moving the Z disks closer together and towards the M line. The amplitude of the A band doesn't change, but both the I bands and the H zone almost completely disappear. This happens because the actin and myosin filaments slide against one another, thus the actin filaments occupy the A band and the H zone.