Muscle atrophy is when muscles waste away. It’s usually caused by a lack of physical activity.

When a disease or injury makes it difficult or impossible for you to move an arm or leg, the lack of mobility can result in muscle wasting. Over time, without regular movement, your arm or leg can start to appear smaller but not shorter than the one you’re able to move.

In some cases, muscle wasting can be reversed with a proper diet, exercise, or physical therapy.

You may have muscle atrophy if:

  • One of your arms or legs is noticeably smaller than the other.
  • You’re experiencing marked weakness in one limb.
  • You’ve been physically inactive for a very long time.

Call your doctor to schedule a complete medical examination if you believe you may have muscle atrophy or if you are unable to move normally. You may have an undiagnosed condition that requires treatment.

Unused muscles can waste away if you’re not active. But even after it begins, this type of atrophy can often be reversed with exercise and improved nutrition.

Muscle atrophy can also happen if you’re bedridden or unable to move certain body parts due to a medical condition. Astronauts, for example, can experience muscle atrophy after a few days of weightlessness.

Other causes for muscle atrophy include:

  • lack of physical activity for an extended period of time
  • aging
  • alcohol-associated myopathy, a pain and weakness in muscles due to excessive drinking over long periods of time
  • burns
  • injuries, such as a torn rotator cuff or broken bones
  • malnutrition
  • spinal cord or peripheral nerve injuries
  • stroke
  • long-term corticosteroid therapy

Some medical conditions can cause muscles to waste away or can make movement difficult, leading to muscle atrophy. These include:

If muscle atrophy is caused by another condition, you may need to undergo testing to diagnose the condition.

Your doctor will request your complete medical history. You will likely be asked to:

  • tell them about old or recent injuries and previously diagnosed medical conditions
  • list prescriptions, over-the counter medications, and supplements you’re taking
  • give a detailed description of your symptoms

Your doctor may also order tests to help with the diagnosis and to rule out certain diseases. These tests may include:

Your doctor may refer you to a specialist depending on the results of these tests.

Treatment will depend on your diagnosis and the severity of your muscle loss. Any underlying medical conditions must be addressed. Common treatments for muscle atrophy include:

Recommended exercises might include water exercises to help make movement easier.

Physical therapists can teach you the correct ways to exercise. They can also move your arms and legs for you if you have trouble moving.

Ultrasound therapy is a noninvasive procedure that uses sound waves to aid in healing.

If your tendons, ligaments, skin, or muscles are too tight and prevent you from moving, surgery may be necessary. This condition is called contracture deformity.

Surgery may be able to correct contracture deformity if your muscle atrophy is due to malnutrition. It may also be able to correct your condition if a torn tendon caused your muscle atrophy.

If malnutrition is the cause of muscle atrophy, your doctor may suggest dietary changes or supplements.

Muscle wasting or atrophy is usually caused by not being able to regularly exercise your muscles. Your inability to move may be be due to an injury or an underlying health condition.

Muscle atrophy can often be reversed through regular exercise and proper nutrition in addition to getting treatment for the condition that’s causing it.