Question

Muscle cells can get longer and shorter. how does this ability fit in with their job in the body?

Answer 1

Because the job of an muscle  will get shorter which will conclude our joints to move. another way is they also would be able to stretch when they are antagonist  muscles :) hope I helped p.s example of an antagonistic pair is the biceps and triceps

Answer 2

Allows them to stretch and compact when needed