If the electrical stimulation is painful but no adequate response is achieved, which adjustment should be made?

• A. Decrease Pulse Duration and Increase Intensity
• B. Increase Pulse Duration and Decrease Intensity
• C. Increase Frequency and Increase Amplitude
• D. Decrease Frequency and Decrease Amplitude

Answer: (A)

When you’re getting a painful stimulus but not a sufficient muscle response, you want to recruit more motor units without increasing the pain. Shortening the pulse duration reduces the charge per pulse, which lessens activation of pain fibers and cutaneous receptors. To still achieve a strong contraction, you raise the intensity to recruit more motor units. This combination—decreasing pulse duration while increasing intensity—targets getting a usable muscle response with the least discomfort. Increasing frequency could smooth the contraction but doesn’t address the pain and can increase fatigue, and increasing pulse duration would raise both charge and pain, making the situation worse.