Muscle Pain: Symptoms, Causes & Treatment

What is Muscle Pain?

The pain of muscle origin is a major health problem. This is one of the most common problems with which individuals approach physicians. Anatomic, physiologic, psychologic, and social factors determine the onset, severity, and duration of the muscle pain or myalgia. Muscle pain is governed by peripheral and central nociceptor mechanisms. Various stimuli sensitize these pain nerve endings or nociceptors, including low pH of muscle tissue and ATP. Myofascial trigger points also lead to muscle pain. These localized areas of thickened muscle fibers, or contraction knots, are tender on touch and stretch. Pain associated with myofascial trigger points arises at three locations – at the sites of contraction knot, at the sites of muscle attachment, and is also referred to other areas. [1]

Muscle Pain Symptoms 

Muscle pain may present as muscle aches and muscle cramps. Muscle spasm is a secondary event to muscle injury, it is characterized by sudden and painful contraction but for a shorter duration as compared to muscle cramps. Common signs and symptoms of muscle pain are as follows. [2]

1. The affected muscle feels stiff and weak
2. Fever
3. Rash
4. Signs of infection such as swelling and redness
5. Soreness and discomfort of the affected muscle
6. Joint pain also accompanies muscle pain  

Causes of Muscle Pain

Muscle pain or myalgia reduces the quality of life and prevents an individual from performing daily activities with ease. The underlying physiologic mechanisms that are responsible for muscle pain are often overlooked by physicians. A better understanding of these etiologies is crucial for better treatment outcomes of muscle pain. To eliminate myalgia, it is important to address these causes at the same time. The six most common causes of muscle pain are listed below. 

Hormonal Imbalance and Muscle Pain

Hypothyroid myopathy is a common term used for describing generalized muscle ache and weakness associated with congenital or acquired defects of the thyroid hormone. Decreased levels of thyroid hormones in the blood, thyroxine (T4) and triiodothyronine (T3), derange cellular metabolism and cause atrophy of the fast-twitch muscle fibers. The muscle fibers lose the ability to break down ATP, which accumulates and elicits muscle pain. [3] Hormones produced by the adrenal gland, particularly the adrenal cortex, also play a significant role in causing muscle pain. Aldosterone deficiency leads to hyperkalemia, which in turn leads to impaired nerve conduction and muscle function. This results in overall muscle fatigue and muscle cramps. [4] Sex hormones are also known to influence pain pathways in men and women. Androgens such as testosterone have antinociceptive properties, hence, testosterone deficiency increases the susceptibility of an individual to muscle pain. On the contrary, female sex hormones such as estrogen and progesterone increase the propensity for muscle pain. Imbalance in hormone levels or their precursors, such as DHEA and pregnenolone causes muscle pain in an individual. [5]

Vitamins Deficiency and Muscle Pain

Vitamins play a key role in regulating body functions. Vitamin B12 is important for nerve and muscle function. Deficiency of vitamin B12 results in peripheral neuropathy, muscle fatigue, weakness, and pain. [6] Deficiency of vitamin C causes musculoskeletal signs and symptoms earlier in the course of the disease. Vitamin C is an important constituent of the healing cycle, thus, deficiency of this vitamin prevents the muscular injuries and tears to heal resulting in muscle ache. [7] Vitamin D deficiency also leads to chronic muscle weakness and pain, owing to the influence of vitamin D on hormones and neurologic functions. [8] Vitamin K is a fat-soluble vitamin that is associated with muscle strength and physical performance as well as regulates inflammatory proteins. Deficiency of vitamin K also renders in myalgia, muscle weakness, and fatigue. [9]

Mineral Deficiency and Muscle Pain

Minerals such as selenium, zinc, magnesium, iron, and iodine are integral components of muscle health. Magnesium imbalance is associated with altered calcium availability to the skeletal muscles that eventually lead to muscle spasms and muscle pain. Zinc and selenium deficiencies are also related to chronic myofascial pain. Iron deficiency limits the ability of hemoglobin in red blood cells to carry an adequate amount of oxygen to the blood. Iodine deficiency is reflected in hypothyroidism as iodine is an important part of the thyroid hormone. Even though minerals are classified as micronutrients, their optimal concentrations are required for muscle strength and power. [10]

Medications That Are Responsible for Causing Muscle Pain

Most common drugs, medications, or medicinal ingredients that elicit muscle pain are mentioned below. These substances alter the metabolism and normal physiology of the muscle.

1. Alcohol is a pro-inflammatory substance that aggravates muscle pain.
2. The drug that lowers cholesterol is known as a statin. Statins cause muscle damage or rhabdomyolysis that leads to muscle pain and muscle spasm.
3. NSAIDs interfere with the normal healing processes and can even worsen muscle aches.
4. Anti-hypertensive drugs alter the mineral component of blood, particularly potassium that interferes with muscle function and gives rise to muscle pain, tenderness, and weakness.
5. Antispasmodic drugs work by altering the pain communication pathways. Even though these drugs provide temporary relief from muscle pain and spasm, they cause muscles to undergo severe pain and spasm. 
6. Anti-diabetic drugs also contribute to muscle pain and weakness by altering the amount of glucose available for normal muscle metabolism.

Other medications that lead to muscle pain include:

1. Thyroid medications
2. Antibiotic therapy
3. Chemotherapy 
4. Steroids 
5. Antiviral drugs
6. Cocaine abuse 
7. Vaccines (intramuscular injections)
8. ACE inhibitors given in neuromuscular disorders 
9. Antacids 
10. Asthma inhalers
11. Beta-blockers for nervous and cardiac disorders 
12. Opioids and other painkillers
13. Drugs to treat osteoporosis 

Infections That Cause Muscle Pain

Infections elicit widespread inflammation in the body. The inflammatory mediators released in the process lead to muscle ache and weakness. The infectious diseases that cause muscle pain include:

1. Cold and flu viruses
2. HIV 
3. Lyme disease 
4. Malaria 
5. Trichinosis 

Diseases That Cause Muscle Pain

A list of diseases, including auto-immune disorders, are also responsible for causing muscle pain.

1. Fibromyalgia 
2. Chronic fatigue syndrome
3. Hypothyroidism
4. Systemic lupus erythematosus
5. Lyme disease
6. Rheumatoid arthritis 

To treat muscle pain, it is imperative to address all of the underlying causes simultaneously. An individual can benefit from the ‘askASTR’ program, which evaluates and interprets nutrient deficiencies and hormonal imbalances in an individual. The program also assists an individual in choosing supplements and other therapies to correct imbalances and treat muscle pain. 

References 

1. Dtsch Arztebl Int. 2008 Mar; 105(12): 214–219. Published online 2008 Mar 21. doi: 10.3238/artzebl.2008.0214 PMCID: PMC2696782 PMID: 19629211
2. Glaubitz S, Schmidt K, Zschüntzsch J, Schmidt J. Myalgia in myositis and myopathies. Best Pract Res Clin Rheumatol. 2019 Jun;33(3):101433. doi: 10.1016/j.berh.2019.101433. Epub 2019 Oct 4. PMID: 31590993.
3. Fariduddin MM, Bansal N. Hypothyroid Myopathy. [Updated 2021 Dec 19]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-
4. Benvenga S, Toscano A, Rodolico C, Vita G, Trimarchi F. Endocrine evaluation for muscle pain. J R Soc Med. 2001 Aug;94(8):405-7. doi: 10.1177/014107680109400810. PMID: 11461987; PMCID: PMC1281637.
5. Maurer AJ, Lissounov A, Knezevic I, Candido KD, Knezevic NN. Pain and sex hormones: a review of current understanding. Pain Manag. 2016;6(3):285-96. doi: 10.2217/pmt-2015-0002. Epub 2016 Mar 17. PMID: 26983893.
6. Regland B, Forsmark S, Halaouate L, Matousek M, Peilot B, Zachrisson O, Gottfries CG. Response to vitamin B12 and folic acid in myalgic encephalomyelitis and fibromyalgia. PLoS One. 2015 Apr 22;10(4):e0124648. doi: 10.1371/journal.pone.0124648. PMID: 25902009; PMCID: PMC4406448.
7. Carr AC, McCall C. The role of vitamin C in the treatment of pain: new insights. J Transl Med. 2017 Apr 14;15(1):77. doi: 10.1186/s12967-017-1179-7. PMID: 28410599; PMCID: PMC5391567.
8. Shipton EE, Shipton EA. Vitamin D Deficiency and Pain: Clinical Evidence of Low Levels of Vitamin D and Supplementation in Chronic Pain States. Pain Ther. 2015 Jun;4(1):67-87. doi: 10.1007/s40122-015-0036-8. Epub 2015 Apr 29. PMID: 25920326; PMCID: PMC4470966.
9. Azuma K, Inoue S. Multiple Modes of Vitamin K Actions in Aging-Related Musculoskeletal Disorders. Int J Mol Sci. 2019 Jun 11;20(11):2844. doi: 10.3390/ijms20112844. PMID: 31212662; PMCID: PMC6600274.
10. Barros-Neto JA, Souza-Machado A, Kraychete DC, Jesus RP, Cortes ML, Lima MD, Freitas MC, Santos TM, Viana GF, Menezes-Filho JA. Selenium and Zinc Status in Chronic Myofascial Pain: Serum and Erythrocyte Concentrations and Food Intake. PLoS One. 2016 Oct 18;11(10):e0164302. doi: 10.1371/journal.pone.0164302. PMID: 27755562; PMCID: PMC5068745.