Muscle Atrophy Types and Causes

Muscle atrophy is a condition in which muscles shrink. It is usually visibly noticeable, causing weakness and decreased muscle tone. There are many causes of muscle atrophy, It often occurs with serious medical conditions, especially with cachexia in cancer and HIV/AIDS. The treatments include different strategies, such as nutrition, exercise, or medication. So, what is muscle atrophy, and what can be done to reverse it?

Older woman working out with weights
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Muscle Atrophy or Muscle Wasting

Muscle atrophy is the loss or decrease of muscle mass. Synonyms include muscle wasting, muscle loss, muscle catabolism, and muscle withering.

There are three main types of muscle atrophy:

  • Physiologic atrophy occurs when muscles aren't used enough, such as with prolonged illness.
  • Pathologic atrophy is the type that occurs as a result of disease, cancer, severe infections, and malnutrition.
  • Neurogenic atrophy is when there is a disruption of the nerve signals to the muscles.

Several of these issues can cause each other and may compound the effects. For example, cancer can cause muscle breakdown due to the disease, and cancer-related fatigue may also lead to a sedentary lifestyle—which causes atrophy to progress further.

Disuse Muscle Atrophy

With muscles, there is definitely a principle of "use it or lose it." If you have been active and exercising, your muscles will get larger and stronger in response. If you stop using certain muscles for too long, they will decrease in size, as well as in strength.

Some common reasons for disuse muscle atrophy:

  • A sedentary lifestyle and lack of regular physical activity can cause disuse atrophy and weakness. The atrophy is usually mild to moderate in severity.
  • Muscle atrophy occurs very quickly when a limb is immobilized. If you have ever had your leg in a cast, you probably how fast you lost muscle in that leg.
  • Prolonged immobilization when bedridden due to disease can lead to severe muscle atrophy that affects many muscles.

Often, people are encouraged to walk and move around while in the hospital—one of the reasons is to minimize muscle atrophy.

A vicious cycle can occur with disuse muscle atrophy. Sometimes pain, such as osteoarthritis or rheumatoid arthritis pain, leads to decreased physical activity and muscle atrophy. And weakness due to muscle atrophy makes it difficult to follow the recommended exercises—which exacerbates stiffness and pain.

Treatment

The treatment for this type of muscle atrophy involves using the muscles with targeted exercises.

Sometimes, resuming normal physical activity can be enough to rebuild muscle if you've only been less active than usual for a short time. For example, after recovering from a bout of the flu, most otherwise healthy people will regain lost weight and rebuild muscle strength after a week or so of regular activity.

Neurogenic Muscle Atrophy

When a nerve that normally stimulates a muscle is damaged, it can no longer trigger muscle contraction that produces muscle activity. Over time, the unstimulated muscles may atrophy. This can occur as a result of peripheral neuropathy, which is a type of nerve damage, and it can also result from spine disease or conditions that affect the brain—like a stroke.

Treatment

Treatment and prevention of neurogenic muscle atrophy involve passive exercises. This means that a therapist, a family member, or a machine will move the muscle to improve blood flow and minimize the breakdown of muscle tissue. In some instances, you might be able to passively move your own muscle if you have strength and control of your other muscles.

Neurogenic muscle atrophy can lead to other issues, such as involuntary muscle twitching or muscle spasticity (extreme stiffness) of the muscle. These complications also require ongoing physical therapy, and sometimes medication.

Pathologic Atrophy

Several medical conditions can cause muscle atrophy due to factors like inflammation, malnutrition, and metabolic problems. These factors can all contribute to muscle breakdown.

Examples include:

Each of these conditions causes atrophy due to different processes. For example, dumping syndrome causes malnutrition, while dermatomyositis and polymyositis cause inflammatory muscle destruction. Treatment of pathologic muscle atrophy varies, depending on the cause.

If you notice that your muscles are getting smaller or weaker, talk to your healthcare provider. You may need a medical evaluation and a treatment plan.

Frequently Asked Questions

  • What is muscle atrophy?

    Muscle atrophy is a loss of muscle tissue. Other terms for muscle atrophy include: 

    • Muscle catabolism
    • Muscle loss
    • Muscle wasting
    • Muscle withering
  • What causes muscle atrophy?

    Muscle atrophy can have a few different causes. In general, muscles that aren’t used can become weaker and smaller. A lack of physical activity is one cause. Nerve damage can also lead to atrophy. In addition, aging, starvation, long-term use of corticosteroids, and many medical conditions can lead to muscle atrophy.

  • Can you rebuild muscles that have atrophied?

    Yes, sometimes, you can rebuild muscles that have atrophied. A combination of physical activity, strengthening exercises, and proper nutrition can often help. You may need physical therapy or rehabilitation to regain muscle strength and muscle mass.

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2 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. U.S. National Library of Medicine: MedlinePlus. Muscle atrophy.

  2. Adams V. Electromyostimulation to fight atrophy and to build muscle: facts and numbers. J Cachexia Sarcopenia Muscle. 2018;9(4):631–634. doi:10.1002/jcsm.12332

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