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Electromyography (EMG) and Nerve Conduction Studies
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Lab Tests

Electromyography (EMG) and Nerve Conduction Studies

EMG and nerve conduction studies are diagnostic tests used to evaluate the health of your muscles and the nerves that control them.

Overview

These tests measure the electrical activity in your muscles and nerves to identify disorders. They are often performed together.

  • EMG test: Measures electrical signals in muscles at rest and during contraction. Healthy muscles should show no electrical activity when at rest.
  • Nerve conduction study: Measures the speed and strength of electrical signals moving along your nerves. Damaged nerves typically show slower, weaker signals.

Why do I need these tests?

Your provider may order these tests if you experience symptoms of a muscle or nerve disorder, such as:

  • Muscle weakness.
  • Tingling or numbness in the limbs or face.
  • Muscle cramps, spasms, or twitching.
  • Paralysis.

What happens during the tests?

EMG Test

A provider inserts a small needle electrode into the muscle. The machine records electrical activity while you relax and while you slowly contract the muscle. You may feel slight pain or discomfort during insertion.

Nerve Conduction Study

Stimulating electrodes are placed on the skin to deliver a mild electrical pulse to a nerve, while recording electrodes measure the muscle's response. This may cause a mild tingling sensation. The speed of the response is recorded as the conduction velocity.

Preparation

  • Inform your provider if you have a pacemaker, cardiac defibrillator, or if you take blood thinners.
  • Wear loose, comfortable clothing.
  • Ensure your skin is clean; do not apply lotions, creams, or perfumes for 24 to 48 hours before the test, as these can interfere with results.

What do the results mean?

Abnormal results may indicate various conditions, including:

  • Carpal tunnel syndrome.
  • Herniated disk.
  • Guillain-Barré syndrome.
  • Myasthenia gravis.
  • Muscular dystrophy (MD).
  • Charcot-Marie-Tooth disease (CMT).
  • Amyotrophic lateral sclerosis (ALS).

Your provider will interpret these results in the context of your symptoms and medical history.

Frequently Asked Questions

bnormal findings can point to conditions such as peripheral neuropathy, radiculopathy, myopathy, or nerve entrapment syndromes. The specific pattern of slowed conduction, reduced amplitude, or spontaneous activity helps narrow the diagnosis. Treatment may involve medication, physical therapy, occupational therapy, lifestyle changes, or, in some cases, surgical intervention. Your clinician will discuss the implications of the results and tailor a management plan accordingly.
fter the procedure, you can usually resume normal activities immediately. However, avoid heavy lifting or strenuous exercise for a few hours if you experienced significant discomfort. If a needle was inserted, keep the area clean and watch for signs of infection. Some clinicians may advise avoiding medications that interfere with nerve function (e.g., certain antibiotics) for a short period, but this is rare. Always follow your provider’s specific post‑test instructions.===
The entire test typically lasts between 30 minutes and 2 hours, depending on how many muscles and nerves are examined. During the EMG, a thin needle electrode is inserted into the muscle, which may feel like a quick pinch or mild discomfort. You may also feel a brief twitch when the muscle is contracted. In the nerve conduction study, small electrodes placed on the skin deliver a mild electrical pulse that can produce a tingling or buzzing sensation along the stimulated nerve. The discomfort is usually brief and tolerable.
Most medications can be taken as prescribed, but some drugs—especially those that affect nerve conduction or muscle excitability, such as certain antiarrhythmics, antiepileptics, or muscle relaxants—may alter test findings. Inform your clinician of all medications, supplements, and over‑the‑counter products you use. In some cases, the clinician may advise temporarily withholding specific drugs, but this decision is individualized and based on your overall health.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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