What Causes Muscle Atrophy?

Muscle atrophy, also called muscle wasting, occurs when the muscles shrink and waste away. The cause is usually lack of activity, often triggered by an injury or disease making it impossible or difficult to move certain muscles. A leg or arm experiencing muscle atrophy might start to look thinner but won't be any shorter than the leg or arm that retains movement. 

There are some cases where muscle atrophy is reversible through physical therapy, regular exercise, and a proper diet. However, this isn't always the case, especially if the atrophy is caused by an underlying medical condition. It's important for individuals to understand the causes of muscle atrophy so they can address them with a medical professional.

Malnutrition

Malnutrition can lead to muscle atrophy as well as other serious effects on the body. Every part of the body needs the right nutrients to function. Vitamins, minerals, and proteins help supply the organs and muscles with the energy they need. In addition to being caused by having too few nutrients, malnutrition can also be caused by having too many of certain nutrients. When the muscles aren't getting the nutrition they need, they can waste away. Billions of individuals throughout the world are malnourished in some way. 

Even if an individual is getting the right amount of nutrients, their muscles can waste away if you aren't getting enough calories. When individuals burn more calories than they consume, their body uses the energy in its fat stores first. But when it goes through the fat stores, it will begin eating away at muscles for energy. If the muscles don't have enough protein to combat this, they can become atrophied and weak. It's also possible to consume too many calories but not get enough nutrients.

Extended Period Of Inactivity

An extended period of inactivity can lead to muscle atrophy. This may occur with just one body part, or it may be widespread throughout the body. For example, if an individual breaks their arm, they may have it immobilized in a sling while it heals. But individuals might also experience muscle atrophy if they live a sedentary lifestyle. Those with a sedentary lifestyle tend to drive to work, sit at a desk for the whole day, sit on the couch when they get home, and then go to sleep. They don't have periods of physical exercise during the week. 

Researchers recommend able-bodied adults get at least twenty minutes of exercise three times a week to avoid muscle atrophy. If individuals lead a sedentary lifestyle, they may be able to reverse the effects of muscle atrophy by starting an exercise regimen. They should keep in mind their body will probably be weak, so it's best to begin slowly. If individuals are concerned about their physical activity levels, they can talk to a doctor or a fitness trainer about the most appropriate exercises.

Spinal Cord Injury

A spinal cord injury can lead to muscle atrophy, particularly when it causes paralysis. With paralysis, an individual's nerves are unable to send the signals to their muscles to move, making it impossible or very difficult to move certain parts of the body. Paralyzed individuals can experience muscle atrophy because of their inability to use their muscles, though there are some treatments to help with this. Peripheral nerve injuries can also lead to muscle wasting when they cause paralysis or loss of feeling. The peripheral nervous system encompasses all the nerves that branch out from the spinal cord and into the rest of the body. 

In addition to muscle atrophy, patients with spinal cord injuries often experience a loss in bone density. This loss of bone density makes individuals more susceptible to fractures. Some patients with spinal cord injuries have experienced fractures during movements as simple as transitioning from a wheelchair to their bed. Some treatments used include standing and electrical stimulation with cycling, walking, and resistance training.

Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a degenerative illness affecting the spinal cord and brain. It is a terminal and chronic illness that causes patients to lose control of their voluntary muscles over time, including the nerves that control limb movements, swallowing, and speech. Researchers have not found a cure for ALS. Because Lou Gehrig, a famous baseball player, received an ALS diagnosis in 1939, this condition has also become known as Lou Gehrig's disease. There are two classifications of amyotrophic lateral sclerosis. 

Around five to ten percent of cases are classified as familial, meaning genetics are the cause, so individuals who have a family member with ALS typically have a higher likelihood of developing. However, ninety to ninety-five percent of cases are sporadic and no cause is known for these cases. Some theories indicate amyotrophic lateral sclerosis may be influenced by immune responses that target motor neurons, free radical damage, buildups of abnormal proteins in the nerve cells, or imbalances in an individual's glutamate levels.

Multiple Sclerosis

Multiple sclerosis (MS) is an autoimmune disease that affects the spinal cord and brain. It occurs when the immune system attacks myelin, a protective sheath covering the nerves. This causes disruptions and communication issues between an individual's brain and the rest of their nervous system. MS can be progressive, meaning it gets more severe over time. It can cause permanent nerve damage and deterioration. The symptoms of multiple sclerosis are extremely varied because they depend on the affected nerves and how much nerve damage has been done. 

Severe MS can cause patients to lose their capability of walking independently or walking at all. Some patients experience remission periods in which they have no symptoms. However, multiple sclerosis remains a chronic disease with no known cure. MS causes muscle atrophy because it impedes muscle movement through the nervous system. Some treatments can help speed recovery and manage symptoms.