Which of these actions happens during muscle contraction

Question

Quizplus · Accepted Answer

During muscle contraction, the H zone (the central part of the sarcomere that is lighter and contains no thin filaments) becomes smaller or disappears as the actin and myosin filaments slide past each other, but the A band (the length of the thick filaments) remains unchanged. The contractile proteins do not actually contract; they slide past each other. The I band (the region containing only thin filaments) also becomes shorter, not unchanged.

Which of These Actions Happens During Muscle Contraction