Physiology The force of muscle contraction can be increased by all of the following except A Increasing the frequency of activation of motor units B Increasing the number of motor units activated C Increasing the amplitude of action potentials in the motor neurons D Recruiting larger motor units 💡 Explanation The force of muscle contraction can be increased by all of the following except ✓ Correct Answer: C. Increasing the amplitude of action potentials in the motor neurons