Electrical current used to make a muscle contract, often in rehab.
NMES delivers an electrical current through surface electrodes over a target muscle or its motor nerve, triggering an involuntary tetanic contraction. It is used when a patient cannot generate an adequate voluntary contraction on their own, most commonly to counter quadriceps inhibition after knee surgery such as ACL reconstruction or TKA.
Post-surgical arthrogenic muscle inhibition can prevent a patient from fully activating a muscle even when they are motivated and pain is controlled, so voluntary exercise alone may not halt strength loss in the early phase. Adding NMES to the exercise program in this window can help preserve or recover quadriceps strength and volitional activation, which informs the decision to layer stimulation onto early post-op rehab rather than waiting for voluntary control to return unaided.
Electrodes are placed over the muscle belly and motor point, and parameters — pulse width, frequency, on/off duty cycle, and intensity — are set to produce a strong, visible contraction against resistance, with intensity increased as tolerance allows since force output is intensity-dependent. It is typically applied for a set number of contractions per session, often alongside or interspersed with voluntary exercise, and progressed as the patient's tolerance and activation improve.
Benefit depends on reaching a sufficiently high intensity to produce a strong contraction; sub-maximal, comfort-limited settings are a common source of disappointing results. It does not replace voluntary strengthening or motor control training, discomfort and patient tolerance can limit achievable intensity, and evidence for added benefit is strongest in the specific context of early post-surgical inhibition rather than as a general strengthening tool for uninhibited muscle.
This guide was auto-drafted and is pending editorial review.