1 Weakness Summary

Weakness refers to the lack of muscle strength. People who have this condition may have to put in the extra effort even to do the daily activities. The lack of strength in muscles may be due to pain.

In such cases, the person may be able to use the muscle but it may hurt. Fatigue is often used synonymously, although the two terms are medically different. Fatigue refers to exhaustion due to lack of energy. Weakness is not a disease in itself but is often a symptom of an underlying condition.

True muscle weakness refers to the inability to perform an activity with a muscle. This is due to the lack or reduction of force with which the muscles work.

In true or primary muscle weakness, the muscles have lesser-than-normal bulkiness and are floppier. This type of weakness occurs with conditions like muscular dystrophy and stroke, where the muscles have lesser power. 

Muscle tiredness or asthenia refers to the fatigue experienced while using a particular muscle. In this case, the muscle is not weak but needs more effort to do the job, which was otherwise done with normal effort or rather effortlessly.

This is usually associated with chronic fatigue syndrome, chronic diseases of the heart, lungs, and other organs, and sleep disorders. Slow energy supply to the muscle is implicated in the development of muscle tiredness.

In some cases, the muscle tires easily, leading to muscle fatigability. Recovery time for the fatigued muscle is more in this case. This condition is more commonly seen in rare conditions like myasthenia gravis.

The differentiating line between the three types of weakness – true muscle weakness, muscle tiredness, and muscle fatigability – and one person may have more than one type of muscle weakness.

Some of the common causes of muscle weakness are a lack of use or muscle fitness, aging, infections, chronic diseases, and pregnancy.

Chronic diseases that lead to weakness include:

Anxiety, depression, and chronic pain are also implicated in the development of this symptom. Muscles may be directly damaged or injured causing weakness and pain in the specific muscles. Certain medications are known to cause muscle weakness.

This includes statins, certain antibiotics, and some anti-inflammatory medicines. Long-term use of steroids is also known to cause weakness. Alcohol and smoking may weaken muscles. Sleep disorders like increase tiredness, resulting in muscle weakness.

Some less common causes of weakness are fibromyalgia, chronic fatigue syndrome, hypothyroidism, electrolyte disorders, muscle inflammation, and cancer. Many nerve conditions like multiple sclerosis, and Parkinson’s disease may damage nerves.

Review of signs and symptoms, evaluation of medical history and physical examination are important in the diagnosis of the underlying condition that leads to weakness. Tests and investigations are generally based on the suspected cause of weakness.

Imaging studies like x-rays, CT scans, ultrasound scan, and MRI are recommended based on the need. Treatment option also depends on the cause of weakness. For increasing fluid intake helps in treating dehydration, if it is the cause of weakness.

In most of the cases, time and rest help to resolve the condition. Weakness caused by a more serious condition may require more aggressive treatment and hospitalization in some cases.

2 Causes

Weakness may be caused by several factors, some common causes of weakness are: 

Lack of muscle fitness – also known as deconditioning, it often results from sedentary lifestyle. As muscles are not used, it get replaced by fat and leads to muscle wasting. These unused muscles get tired easily with normal activities.

Ageing – strength and bulkiness of muscles reduce with age, leading to weakness. Power and muscle of the strength can be maintained to a certain extent with a moderate exercise routine.

Infections – many normal infections lead to temporary weakness of muscles. Infection is the cause of inflammation that causes fatigue or muscle weakness. Flu, glandular fever, hepatitis C, Lyme disease, malaria, syphilis, and tuberculosis, are all known causes of muscle weakness.

Pregnancy – anemia and high levels of steroids during pregnancy leads to tiredness.

Chronic diseases – many chronic diseases lead to muscle weakness. This includes: 

  • Peripheral arterial disease – this condition is caused by narrowing of blood vessels. This reduces the supply of oxygen and nutrients to muscles, weakening the muscles.
  • Diabetes – raised levels of sugar in blood cause weakness. Diabetes also increases the risk of peripheral artery disease.
  • Heart disease – heart disease affect the supply of blood to muscle, leading to weakness.
  • Chronic lung disease – many lung conditions like chronic obstructive pulmonary disease (COPD) affect the ability of body to take in oxygen. This reduced oxygen supply makes the muscle easily tiring.
  • Chronic kidney disease – chronic conditions of kidney is characterized by salt imbalance and buildup of toxins, both of which leads to true muscle weakness.
  • Anemia – anemia reduces the ability of blood to carry oxygen, leading to muscle tiredness.

Certain mental conditions affect the muscles leading to weakness. Anxiety increases the adrenaline activity in body, leading to generalized weakness. Depression may also cause generalized tiredness and muscle weakness. Chronic pain is another cause tiredness and muscle weakness.

Injury and trauma to muscles cause inflammation and pain, two conditions that lead to muscle weakness.

Certain medicines are known to have weakness as one of the side effects or as an allergic reaction. This includes statins, some antibiotics, and certain anti-inflammatory pain killers. Muscle weakness is also caused by the use of steroids for a long time. Some heart medicines, anti-HIV medications, and medications for hyperthyroidism are also implicated in muscle weakness.

Alcohol and smoking may cause significant weakness of muscles

Sleep disorders that affect quality sleep may increase muscle weakness and tiredness. This includes insomnia, restless leg syndrome, depression, shift work, and chronic pain are known causes of weakness.

Some less common causes of muscle weakness include:

Neurological conditions and spine-related conditions can cause muscle and generalized weakness. Nerve conditions like multiple sclerosis, Guillain-Barré syndrome, and Parkinson’s disease cause muscle damage, and thus weakness.

Genetic conditions that affect muscles are some rare causes of weakness. Muscular dystrophies, including sarcoidosis and amyloidosis, and myotonic dystrophy affect muscles. Motor neuron disease, myasthenia gravis, and poison may also weaken muscles.

3 Diagnosis and Treatment

Review of the present condition is the first step in the diagnosis of the underlying condition. The doctor may analyze the onset of this symptom and the factors that exacerbate or improves a weakness.

Information any recent travels, or personal information including loss of weight may also provide clues regarding the cause of weakness. During the physical examination, the doctor may feel the affected muscle to check for inflammation, tenderness, and fatigability.

They may also check for balance and coordination of muscles during different activities. Blood tests are used to check for hormonal abnormalities, and differences in levels of electrolytes and blood cells.

Other tests are recommended based on the probable cause of weakness. Nerve studies are suggested to evaluate the functioning of nerves. Muscle biopsy is used to check for muscle inflammation or damage.

Imaging studies are also used to diagnose internal conditions that may lead to weakness. X-rays, CT scans, Ultrasound scans, and MRI are the commonly used imaging methods for the diagnosis of the cause. Brain scan and electrocardiogram are less commonly used when cardiac issues of brain disorders are suspected.

Treatment of muscle weakness depends on the diagnosis of the cause. For conditions like the flu or the common cold, no specific treatment is required. Weakness resolves as the condition are better.

Increasing fluid intake is the best way to control weakness caused by dehydration. Severe symptoms of dehydration may require hospitalization. Medications are given to increase the blood pressure levels and intravenous fluids are given to control dehydration.

Blood loss leading to weakness may need iron supplementation, particularly if the patient is iron deficient. Blood transfusion may be needed in severe cases.

Weakness can be improved with home treatment in most of the cases. Getting adequate rest is one of the important steps to control weakness and tiredness. Fatigue or weakness can be reduced by alternating rest with exercise.

Avoid or limit the intake of medicines that cause weakness. This should be done in discussion with the doctor. Eating a balanced diet will help to improve energy levels. Reduce the intake or alcohol and other substances that lead to fatigue. Get enough physical activity to avoid deconditioning of muscles.

Develop good sleep habits like avoiding:

  • Disturbances while sleeping
  • Eating before going to bed
  • Watching TV before sleeping

But if any new symptoms develop even after home treatment, it should be brought to the attention of the physician. A doctor’s visit is recommended if the symptoms last for more than two weeks, or if they become severe.

Some home remedies tried to reduce weakness include bananas, almonds, milk, gooseberry, licorice, and ginseng. Essential oils massages using lavender oil, jojoba oil, and olive oil are used to increase strength and energy. These oils are applied over the joints and allowed to be absorbed by the skin.

4 Related Clinical Trials