A physical therapist uses electromyographic biofeedback to improve a patient's ability to recruit the vastus medialis obliquus muscle. After initiating the intervention the therapist observes that the patient is unable to generate the anticipated level of audio and visual activity on the biofeedback unit. What is the MOST appropriate therapist action?

• A. Increase the size of the surface electrodes
• B. Remove oil and dead skin from the target area using an alcohol prep pad
• C. Select a more conservative strengthening intervention
• D. Modify the location of the surface electrodes

Answer: (D)

EMG biofeedback depends on detecting electrical activity from the target muscle, and electrode placement directly determines what signal is captured. If the unit isn’t showing the expected audio or visual feedback, the most effective first step is to reposition the electrodes so they sit over the muscle belly of the vastus medialis obliquus and align with its fiber direction. This improves the likelihood that the device picks up the intended muscle activity rather than distant or non-target signals, making the feedback meaningful for training. Skin prep and electrode size can help after you’ve found a good placement, but the primary action is adjusting where the electrodes are placed to optimize detection of the VMO signal.