Which parameters influence sensation, contraction, heating, and comfort during electrotherapy?

• A. Pulse duration, frequency, and duty cycle.
• B. Amplitude only.
• C. Electrode size only.
• D. Pulse duration only.

Answer: (D)

Pulse duration governs how long each pulse affects the tissue, which directly sets how much charge is delivered per pulse and how long nerve fibers are depolarized. This combination determines how many fibers are recruited (sensations and whether a motor response occurs) and how much energy is deposited into the tissue (which drives heating). As the pulse duration increases for a given current, more nerve fibers can be activated and more energy is delivered with each pulse, leading to stronger sensations, a greater potential for contraction, and more heating, all of which influence how comfortable the experience is. While amplitude, electrode size, and other factors also matter, pulse duration links sensation, contraction, heating, and comfort most directly by controlling the total charge per pulse and the duration of neural excitation.