Neuromuscular Electrical Stimulation in Physical Therapy

Electrical stimulation applied to a woman's rotator cuff.
Your physical therapist may apply NMES to your muscles to help them function better. E+/Getty Images

After injury or illness, muscle weakness may make it difficult to perform basic functional tasks like walking, running, or climbing stairs.  Your physical therapist can help prescribe exercises to increase your strength to help improve your functional mobility.  He or she may also use various treatments and modalities to help get you back to your normal lifestyle.

Neuromuscular electrical stimulation (NMES) is a common physical modality used in physical therapy to help improve the way your muscles contract.

 It is a type of electrical stimulation that is used if you have weakness in one or more muscles.  It is used to help re-educate your muscles to contract properly.  It can also be used to treat muscular spasm.

How is NMES Applied?

Neuromuscular electrical stimulation is applied to your body with a small electrical stimulation unit.  This unit can be battery powered or plugged into an electrical outlet.  Small electrodes are applied to your body on the muscle or muscle group that is weak.

Once the NMES unit is applied to your body, your physical therapist will turn the unit on and increase the electrical intensity applied to your muscle.  The electrical impulses that are moving through the electrodes help to artificially contract your weakened muscle.

What Does NMES Do?

While the NMES is applied to your body, the electrical impulses contract your muscle for you.  The artificial contraction helps to re-educate your muscle so that it contracts properly.

 This can help improve the way your muscle works.  While the NMES unit is working to contract your muscle, you should be using your muscle as well.

For example, if you have knee surgery, it may be difficult to elicit a forceful contraction in your quadriceps muscle on top of your thigh.  This is often due to a condition called neuromuscular inhibition.

 Essentially your nervous system decreases input to your muscle or muscles after injury.  Your PT may apply NMES to your quadriceps muscle to help improve the way the muscle works to create a forceful contraction.

Neuromuscular electrical stimulation can also be used to treat spasm in the body.  The NMES unit contracts your muscle many times over a 15 to 30 minute period, and this is thought to fatigue your muscle so it will not be in a constant state of contraction and spasm.

What Does NMES Feel Like?

When your physical therapist first applies the NMES electrodes to your muscle and starts to increase the intensity, you will feel a slight tingling sensation.  Your physical therapist should slowly increase the intensity until you can feel and see your muscle contract.  Sometimes the tingling sensation is too intense and a muscle contraction cannot be achieved.  If this is the case, your PT can make some adjustments to the NMES unit to increase your comfort while achieving a strong muscle contraction.

In general, the intensity of the NMES should be increased until a strong, but comfortable, muscle contraction is achieved.  The NMES unit will contract your muscle for a short period, usually 10 to 30 seconds, and then it will shut off to provide a brief rest period.  Your physical therapist will set the NMES unit to make your muscle contract and then relax repeatedly.  The amount of time your muscle works and rests is called the duty cycle.

When the NMES unit is on and contracting your muscle, you should be working to contract your muscle as well.  When the NMES unit turns off and gives you a short rest period, you should relax your muscle.

Exercise after NMES Treatments

Once​ your NMES treatment is finished, usually after 15 to 30 minutes, your physical therapist should prescribe specific exercises to help improve your muscle function.  For example, if you have shoulder surgery and your rotator cuff muscles are not contracting properly, your physical therapist may use NMES on those muscles to help them contract better.  Once the treatment is finished, you should perform specific exercises to help train your rotator cuff to work properly without the NMES.  Active range of motion exercises or resistance band exercises can be done to accomplish this.

If you are having difficulty contracting a muscle or group of muscles after injury or surgery, your physical therapist may elect to use NMES for muscle re-education.  This can help your muscle start contracting properly and can make exercises to strengthen that muscle more effective.  By improving your muscle's contraction with NMES and by working hard in physical therapy, you may be able to quickly return to your previous level of activity and function.

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