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

Fact 2: Exercise causes muscles to contract.

Given the two facts above, answer the question "What does exercise cause muscles to do?" with the following options: 
- rapid expansion
 - aerobic capacity
 - movement
 - to move people
 - Get shorter
 - It will move.
 - Dehydration
 - improve


 

     Get shorter    