Fact 1: Muscle contraction occurs when muscle fibers get shorter.

Fact 2: Muscle activation is a prerequisite for muscle contraction.

Given the two facts above, answer the question "what happens to fibers after muscle activation?" with the following options: 
- It expands
 - Localized damage
 - It decreases
 - get shorter
 - they bend
 - rapid expansion
 - sweating
 - movement


 

    get shorter     