Muscle weakness - causes, symptoms and therapy

Muscle weakness shows up when we can no longer move as we want because our muscle strength and muscle tension decrease. Doctors speak of myasthenia.

Disrupted nerve impulses

Do you suffer from muscle weakness? Then the transmission of the signals from the nerve to the muscle no longer works as it should.

Usually acetylcholine (ACh) is released when a nerve impulse reaches the nerve end. The substance docks onto Ach receptors in the muscles. This causes the muscle to contract. The ACh then releases from the receptors, the cholinesterase breaks down the transfer agent and the nerve endings absorb it. ACh builds up again and the process repeats itself.

Myasthenia gravis produces antibodies that bind to the receptor in the muscle, just like the transfer agent. However, these antibodies cannot trigger a muscle contraction, but they block the receptors for ACh.

The ACh is broken down, but the antibodies remain. Result: The strength of the muscles drops. If the ACh forms again, the muscles can work fully again.

The thymus

The thymus is an organ of the immune system behind the breastbone. Muscle weakness is often related to disorders of the thymus. After all, 15% of those suffering from muscle weakness have tumors on the thymus, so-called thymones.


Typical is a muscle weakness that gets stronger in the evening and then passes - without pain. Ocular myasthenia is widespread, in which those affected see double images or their eyelids hang down.

Generalized myasthenia is more severe. All muscles of the skeleton can be involved here, especially the muscles on the arms and legs, but also the muscles that make it possible to speak and swallow.

Those who suffer from it have problems getting up from bed, climbing stairs or getting the laundry out of the machine.

If the myasthenia affects the throat or respiratory muscles, this leads to chewing problems, frequent swallowing and mumbling, a toneless voice, a slight cough or rapid breathing while talking. In an emergency, respiratory paralysis and severe swallowing disorders can occur.

The symptoms are very different: some only feel a little weaker than usual, others are as weak as if they were paralyzed.

A general muscular weakness manifests itself either as permanent fatigue or through very rapid fatigue during physical work.

The specific symptoms indicate the cause. If the myasthenia occurs suddenly, then there is probably an acute infection or a stroke. Muscle weakness that is developing more slowly suggests another suspicion: mineral deficiency, rheumatic diseases or side effects of medication. On the other hand, if the complaints become more severe, then this indicates genetic disorders of the muscles or diseases of the metabolism.

Symptoms for muscle weakness include: tremors, muscle pain, paralysis, gait disorders, visual disturbances, speech, swallowing and consciousness disorders.


Muscle weakness can be as harmless as life-threatening. Muscular weakness can have many causes. Harmless triggers include an unhealthy diet and the consequent lack of minerals, lack of exercise or age.

In addition, there are infections, diseases of the nervous system and muscles or a stroke, as well as genetic diseases and mental disorders.

The most common cause is muscle overload, sore muscles, or torn muscle fibers.

Diseases of the nerves or muscles that cause muscle weakness include muscle inflammation, muscle wasting, amyotrophic lateral sclerosis, severe muscle weakness, damaged nerves in diabetics and alcoholics, polio, Lyme disease, multiple sclerosis, Parkinson's disease, herniated disc, stroke, soft tissue rheumatism, Down's syndrome, meningitis , Brain and spinal cord tumor.

There are also diseases that do not specifically affect the nerves or muscles: infectious diseases such as flu, anemia, underactive thyroid, thrombosis, depression.

Magnesium deficiency

Magnesium is necessary for the electrolysis budget, and if it does not work, the muscles cannot work. If the body lacks magnesium, it causes muscle weakness.

An important symptom of magnesium deficiency is muscle spasms that accompany muscle weakness. They usually occur at night, which then lowers the already low magnesium level. Because magnesium is needed to relax muscles, they cramp when there is not enough.


If there is no serious underlying illness, muscle weakness can be prevented with simple means: Reduce your cigarette and alcohol consumption and sleep well. If you already suffer from muscle weakness, strength training helps to build muscle.

Chronic diseases such as multiple sclerosis cannot be combated by prevention. Nevertheless, a healthy diet also helps to limit muscle weakness.

If the myasthenia is due to excessive strain on the muscles, then recovery helps. Take regular breaks.


If you cannot explain your weakness, for example as a result of exercise, hard physical work or bedriddenness, then you should definitely see a doctor, because this is how a serious illness can be expressed. If the symptoms suddenly appear, you should go to a hospital immediately - it could be a stroke.

The family doctor first asks you about the medical history, looks at you, probes you, listens to you, knocks you off and checks the vital functions. If there is a suspicion of a basic illness, specific examinations follow in order to recognize this illness.

The doctor asks when the muscle weakness first appeared and at what times it appeared, which muscles are affected, whether it came suddenly or gradually, whether you can remember a possible trigger, such as symptoms after excessive weight training.

He is also interested in the diagnosis of whether you suffer from previous or comorbidities, whether you have had surgery or accidents, whether your family experienced similar symptoms.

Are you allergic to certain things, take medication, are you exposed to a lot of physical or psychological stress at work? Do you exercise enough, eat a balanced diet, sleep enough, drink a lot of coffee, smoke, use alcohol or drugs? All of this is important to create a clinical picture.

The doctor now uses his own strength to check how strong the individual muscles of the patient are, for example by flexing the arm in the elbow. You can check whether the muscle weakness is dependent on stress by repeatedly crumpling up paper, for example.

Exercises such as getting up from a crouch, writing, standing or walking show whether the skeletal muscles are disturbed.

The doctor also checks nerve functions, reflexes, touches and the movement sequence. In addition, if specific diseases are suspected, there is a blood test, a measurement of the nerve conduction speed by the doctor irritating the nerves electrically, a measurement of the muscle currents, which proves whether the muscles are intact, i.e. it is a nerve problem. Tissue samples and genetic examinations, as well as computer tomography may be added.

Therapy for muscle weakness

In the case of basic diseases, these must be tackled. For example, the specialist removes thymomas during surgery or radiation therapy.

Medicines that slow down the immune system prevent antibodies from forming. These include corticosteroids with azathioprine. If the muscle weakness is "only" a symptom, it is nevertheless recommended to alleviate this symptom. Pyridostigmine and neostigmine stop the breakdown of ACh between muscle and nerve. Plasmapheresis cleans the blood of antibodies.

Treatment of the basic disease

This depends on the illness. In the case of a herniated disc, surgery is the order of the day, in the case of a mineral deficiency, for example, an iron or vitamin preparation. Anti-inflammatory drugs should be used for muscle inflammation.

Hereditary muscle diseases can usually not be combated by the cause. Here the treatment serves to alleviate the muscle weakness itself.


Physiotherapy accompanies all therapies for muscle weakness, regardless of the cause. Massages, heat treatments and alternating baths also improve the condition of the muscles.

Lambert-Eaton syndrome

Lambert-Eaton syndrome is caused by antibodies at the nerve end that prevent the release of ACh.

It is not an independent disease, but a side effect of cancer, especially of bronchial tumors. Muscle weakness is often shown on the legs. As a drug, 3,4-diaminopyridine has proven successful.


Those suffering from muscle weakness should check whether they are taking medications that increase their symptoms. These include aminoglycosides, beta blockers, drainage agents and muscle relaxants. (Dr. Utz Anhalt)

Author and source information

This text corresponds to the specifications of the medical literature, medical guidelines and current studies and has been checked by medical doctors.

Dr. phil. Utz Anhalt, Barbara Schindewolf-Lensch


  • Deutsche Myasthenie Gesellschaft e.V .: Lambert-Eaton syndrome, (accessed 09.09.2019), DMG
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  • Michael Benatar: Myasthenia Gravis and Myasthenic Disorders, Neurology Jul 2013, 81 (1) 99; DOI: 10.1212 / WNL.0b013e318297ef4d, (accessed on 09.09.2019), neurology
  • D. Heuß et al .: Diagnostics and differential diagnosis in myalgia, German Society for Neurology (DGN), (accessed on 09.09.2019), DGN

ICD codes for this disease: G70.0ICD codes are internationally valid encodings for medical diagnoses. You can find yourself e.g. in doctor's letters or on disability certificates.

Video: Muscle Fatigue, Causes, Signs and Symptoms, Diagnosis and Treatment. (January 2022).