During concentric isotonic contraction of a skeletal muscle fiber, which of these occurs?
A) sarcomeres lengthen
B) A bands shorten
C) I bands shorten
D) A bands lengthen
E) thin filaments shorten

Question

Quizplus · Accepted Answer

During concentric isotonic contraction, the force generated by the muscle fiber is greater than the opposing load, causing the I bands to shorten as the actin filaments slide over the myosin filaments towards the center of each sarcomere. This shortening of the I bands results in a shorter overall length of the muscle fiber. The A bands, which contain the myosin filaments, do not change in length during a concentric contraction. The thin filaments, specifically the actin filaments, do not shorten but move towards the M line in the center of the sarcomere, resulting in the shortening of the I bands.

During Concentric Isotonic Contraction of a Skeletal Muscle Fiber, Which