The Link Between Long COVID and Muscle Weakness

Long COVID is characterized by the persistence of symptoms for weeks or months after having COVID-19. One of the most frequent symptoms is muscle weakness, which can be debilitating and even cause a person to have difficulties exercising or performing day-to-day tasks.

In this article, we will shed light on the connection between long COVID and muscle weakness, exploring the causes, symptoms, and management options.

What is long COVID, and what are its symptoms?

Post-COVID-19 syndrome, or long COVID, refers to the persistence of symptoms for at least three months after first contracting the COVID-19 virus (acute infection).

It is estimated that approximately 57% of adults in the U.S. had COVID-19 at some point, and out of those, around 9% are currently experiencing long COVID symptoms.

The most common symptoms reported by people who suffer from long COVID include fatigue, breathing difficulties, and muscle weakness, which can make it difficult to exercise or even perform everyday tasks.

What increases the risk of long COVID?

Anyone infected by COVID-19 can develop long COVID, even those who were asymptomatic at first.

Researchers are still looking into the factors that increase a person’s chance of developing long COVID; however, it seems to be more frequent in:

• People who had severe acute COVID-19 disease.
• Unvaccinated people.
• Individuals with underlying medical conditions (e.g., diabetes, obesity, asthma, etc.).

How long COVID impacts muscle health

The COVID-19 virus can affect different organs and systems in the body, including the musculoskeletal system.

Muscle weakness, muscular pain (myalgia), and fatigue are common in people who have long COVID and can happen as a result of several contributing factors, such as:

• Direct viral effect. The COVID-19 virus can cause inflammation and damage to the muscles, which can become chronic (long-term) and persist beyond the typical recovery period of the disease.
• Autoimmune response. As a result of the COVID-19 infection, the immune system triggers a response to kill the invading virus and protect the body from damage. However, in some cases, this response can be exaggerated, prompting the immune system to start attacking healthy body cells and tissues by mistake, including those of the musculoskeletal system.
• Muscular deconditioning. During the acute period of the infection, most people experience debilitating symptoms that prevent them from staying active and performing their usual activities for several days or weeks. On top of that, people who experience moderate to severe COVID-19 symptoms usually need to have prolonged bed rest. This lack of physical activity leads to muscular deconditioning, which makes it more challenging for individuals with long COVID to regain their usual strength.
• Nutritional status. A poor nutritional status is associated with muscular dysfunction and slower muscular healing in people with long COVID.

The science behind exercise difficulty after long Covid

Although we still don’t know the exact mechanisms underlying the transition from acute COVID-19 to long COVID, we do know that once the COVID-19 virus enters the body, it attaches itself to an enzyme called ACE2 (angiotensin converter enzyme 2). The ACE2 enzyme can be found in most organs and tissues in the body, including the muscles.

Once the virus enters the body’s cells, it causes inflammation and damage, which eventually leads to the onset of COVID-19 symptoms, including muscle weakness and pain.

There is evidence that once the COVID-19 virus enters the cells, it disrupts the activity of mitochondria — the energy ‘factories’ of the body — which contributes to early muscle fatigue.

A study conducted in 2022 about muscular fatigue related to long COVID found evidence of inflammation and abnormal changes in the muscles and small blood vessels of people reporting muscular weakness, pain, and fatigue 5–14 months after having COVID-19.

These findings were later supported by two more studies carried out in 2023 — Post-COVID exercise intolerance and 2024 Long COVID muscle abnormalities — the latter of which also found evidence of severe debilitating soreness after exercising.

Based on the existing research, there is enough data to confirm that long COVID may cause:

• Persistent inflammation of the muscles
• Abnormal changes in the muscle tissue
• Reduced energy supply to the muscle
• Decreased blood flow to the muscles

Why are my muscles not the same after long COVID?

As stated before, long COVID is related to significant abnormal changes in the muscles of affected people.

These muscular changes affect not only the capacity of the muscle to respond to stimuli but also your capacity to exercise, resulting in muscular deconditioning over time. Muscular deconditioning leads to muscle mass loss and a decrease in muscle quality, which eventually results in reduced strength.

A study by Ramírez-Vélez et al., published in the Journal of Applied Physiology in 2022, found that individuals with long COVID had a significant decrease in absolute and relative muscle strength when compared to those with similar characteristics who never had COVID-19.

What are the symptoms of muscle weakness due to long COVID?

People affected by long COVID can have a wide variety of symptoms, including muscle weakness, often characterized by:

• Difficulty carrying out normal day-to-day tasks
• Having trouble resuming physical exercise or activities
• Getting tired very easily, even after minimal efforts
• Heaviness sensation in the limbs
• Muscular pain

How long can muscle weakness last after long COVID?

Every person is different, so the duration of how long muscle weakness lasts varies.

Several factors can contribute to persistent muscle waste (atrophy) and strength reduction; for instance, extended periods of bed rest may promote or worsen muscle weakness and fatigue.

That said, there have been reports of muscle weakness symptoms lasting for up to 14 months after the COVID-19 infection.

Managing muscle weakness and long COVID

Since muscle weakness can last for several weeks or months, learning how to manage it can be crucial for regaining a sense of control and freedom.

Even though there is no one-size-fits-all solution, some things that can help include:

• Eating a well-balanced diet
• Staying hydrated
• Getting enough sleep
• Engaging in light and progressive exercise

Muscle weakness is a challenging and frustrating symptom of long COVID, but with the right rehabilitation program specifically tailored by a healthcare professional, it can become less burdensome, and the affected person can improve their quality of life.