Popular Tests for Muscle Weakness

Updated: Jun 18, 2020


In order to determine the depth and severity of your muscle weakness, the first step your doctor will take is to ask you about other symptoms and carry out an examination.  The provisional physical exam is likely to be simple, and it may not be adequate to enable an accurate diagnosis. If this is the case, there are further tests for muscle weakness that might be necessary. Read on to find out more about some of the most well-known.

Popular Tests for Muscle Weakness

3 Types of Muscle Weakness

Complaints of muscle weakness will often present some difficulty to a doctor, because this can refer to several different types of muscular problems. They are generally categorized into three; however, the definitions between them can be somewhat blurred:

  • True muscle weakness. This refers to an instance when you are unable to use a specific muscle at all.

  • Muscle tiredness. This describes when you can use your muscles, but it requires more effort than usual, and causes physical exhaustion quickly. 

  • Muscle fatigability. This is when your muscle still functions but feels weak quickly and takes a long time to recover.

Tests for Muscle Weakness 

To properly determine which type of muscular weakness you have, and to then look into the possible reasons behind it, it might be necessary to undergo specific tests. The following are the most common.

Physical examination

During your initial appointment, it is probable that your doctor will want to feel your muscles when flexed or watch you carry out simple tasks such as walking or lifting an object. This will enable them to check whether or not your muscles are inflamed, and whether they are functioning abnormally. Watching you use the muscles should help a doctor to see if you are experiencing unusual and concerning fatigue.

Blood tests

If your doctor is not satisfied that he/she can pinpoint your condition after solely a physical exam, the next step is usually a blood test for muscle weakness. Most of the time, they will call for enough blood samples to be taken to enable testing of several possible issues. Among a multitude of problems, these can be used to check to see if nerves have been damaged, if muscle cells have been impaired, or if you have an autoimmune disorder that causes the immune system to attack the muscle.

Electromyogram (EMG)

This test is particularly useful when trying to evaluate muscle efficiency. It involves the use of surface or needle electrodes, which will emit a small electrical current localized in specific areas of the body. During the test, you will be asked to contract and relax different muscles, and the technology will measure their behavior, enabling the doctor to assess to competency of the messages between your brain and your muscles.

Muscle biopsy

It might be necessary to perform a procedure known as a biopsy to test the condition of your muscles. A small piece of muscle tissue will be removed, either via a needle or by making a small incision. The sample will be sent away for testing to see if there is an infection, disease, inflammation, or other unusual aspect affecting it. 

Usually, the above tests are sufficient to enable a doctor to discover why you might be suffering from muscle weakness. While they can sometimes be uncomfortable, it is important not to worry about them too much because they are routine and trusted. If you are experiencing muscle weakness, your doctor will explore some possible causes with you and talk you through any tests that they deem necessary.

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