In electrical stimulation, electrode size and placement primarily determine what?

In electrical stimulation, electrode size and placement primarily determine what?

• A. Frequency of current
• B. Number of motor units stimulated
• C. Depth of tissue heating
• D. Battery life

Answer: (B)

Electrode size and placement determine how electrical current is distributed in tissue, which controls how many motor units are recruited. Smaller electrodes concentrate current into a smaller area, producing more focal activation of nerves beneath them, while larger electrodes spread current over a wider area, engaging motor units across a broader region. The result is that the number of motor units stimulated depends on where and how the current is delivered, not on the device’s frequency setting, the depth of heating (which depends on intensity, duration, and tissue properties), or the battery life (which depends on overall power use).

Electrode size and placement determine how electrical current is distributed in tissue, which controls how many motor units are recruited. Smaller electrodes concentrate current into a smaller area, producing more focal activation of nerves beneath them, while larger electrodes spread current over a wider area, engaging motor units across a broader region. The result is that the number of motor units stimulated depends on where and how the current is delivered, not on the device’s frequency setting, the depth of heating (which depends on intensity, duration, and tissue properties), or the battery life (which depends on overall power use).