What is the interval between one pulse and the next?

• A. Amplitude
• B. Phase duration
• C. Interpulse interval
• D. Current type

Answer: (C)

Interpulse interval is the time between one pulse and the next, and it determines the stimulation frequency (frequency ≈ 1 divided by the interval). This directly answers the question about how far apart successive pulses are. Amplitude is about how strong each pulse is, not the timing. Phase duration refers to how long a single phase lasts within a pulse, which describes pulse shape rather than spacing. Current type describes whether the waveform is AC, DC, or pulsed, again about the nature of the current rather than when pulses occur. Knowing the interpulse interval helps predict the response: shorter intervals mean higher frequency and can lead to more continuous or stronger contractions, while longer intervals allow more recovery time between pulses.