Why was it important to rest between contractions during the force/intensity portion of the experiment? What would have happened if there were no breaks? 2.Hypothesize what causes a difference between fatigue and rigor mortis, even though both conditions happen when ATP is depleted. On a molecular scale, consider the role of calcium ions and how their presence or absence would affect the outcome. 3.List 2 advantages of a motor system that is organized into motor units rather than a system where the whole muscle is innervated in an all-or-none fashion. When is it more advantageous to have many motor units of only a few muscle fibers each? When is it more advantageous to have fewer motor units that have many muscle fibers?