If you wanted to pick up something heavier than your pencil (such as your textbook), you would need to have a stronger muscle contraction. In what way might you accomplish this?
a. stimulate more muscle cells
b. decrease the frequency of stimulation
c. decrease the refractory period
d. increase the frequency of stimulation
e. Both a and d are correct.

a. Stimulate more motor cells.

Explanation:

When a person want to pick up something heavier his muscles do contact and increases the strength to be able for you to pick up something heavy. When pencil is lifted up there is less pressure on the elbow muscles but when a text book or a heavy object is lifted it results in contraction of muscles. Lifting heavier weights also stress the nervous system of the human body. The correct answer is to stimulate more motor cells. One axon plus all of muscle fiber equals to one motor cell.