Which statement best describes a characteristic of denervated muscle stimulation compared to innervated muscle stimulation?

• A. Requires longer pulse duration (phase charge)
• B. Requires higher frequency
• C. Requires higher amplitude
• D. Requires shorter pulse duration

Answer: (A)

Denervated muscle stimulation relies on directly activating the muscle fiber membranes rather than triggering an action potential through a nerve. Because the denervated muscle membrane has a higher threshold and responds more slowly, it needs a longer duration of current per phase to deliver enough charge to reach depolarization. That makes longer pulse durations the defining requirement for producing contraction in denervated muscle, compared with innervated muscle where short pulses are sufficient.

Frequency isn’t the defining difference here; innervated muscle can be driven with higher frequencies to produce smooth contractions, while denervated tissue still needs the long pulse duration to elicit a response. Amplitude may need to be increased, but the key characteristic that sets denervated stimulation apart is the need for longer pulse duration.