What Causes Muscle Contractions to Be Graded

Question

What causes muscle contractions to be graded?
A) increasing stimulus frequency
B) both increasing stimulus strength and increasing stimulus frequency
C) increasing stimulus strength

Accepted Answer

Muscle contractions are graded based on both increasing stimulus strength and increasing stimulus frequency. Increasing stimulus strength allows for more motor units to be activated, while increasing stimulus frequency enhances the force produced by each muscle fiber through temporal summation.