What are muscle cramps?

Muscle cramps are painful, sometimes disabling, involuntary contractions of muscles under voluntary control (skeletal muscle) caused by abnormal functioning of the nerves which control the muscles. Cramps are exacerbated when the nervous system is stressed.

Muscle cramps are a symptom of a multitude of underlying medical conditions. Muscle cramps can be classified as:

  • Paraphysiologic;
  • Idiopathic; or
  • Symptomatic.


Types of muscle cramps


Muscle crampsParaphysiologic muscle cramps

Paraphysiologic muscle cramps are commonly experienced, but they have no underlying medical condition. This includes cramps associated with:

  • Pregnancy: Up to 30% of pregnant women will experience leg cramps during their pregnancy, most frequently during the last trimester;
  • Exercise: The cause of exercise-associated muscle cramps (EAMC) is still largely unknown. It is believed to be highly related to physiological stress such as dehydration or after excessive physical strain.

 

Exercise-associated muscle cramps
For more information see, Exercise-Associated Muscle Cramps (EAMC)


Idiopathic muscle cramps

Most people at some time of their life will experience an idiopathic muscle cramp. These cramps usually occur at night in the leg and foot muscles and can be triggered by even the slightest shortening of skeletal muscle.

Idiopathic muscle cramps can be classified into the following:

  • Nocturnal cramps: Cramps that occur at night when in bed;
  • Autosomal dominant cramping disease: An inherited disease involving recurrent muscle cramping;
  • Continuous muscle fibre activity syndromes: Including Isaac’s syndrome, Stiff-man syndrome and cramp fasciculation syndrome (the uncontrollable twitching of muscles beneath the skin);
  • Sathoyoshi’s syndrome: Syndrome of progressive muscle spasm which includes diarrhoea and alopecia;
  • Myokymia: Spontaneous muscle quivering;
  • Myokymia-hyperhidrosis syndrome: Myokymia paired with excessive perspiration;
  • Familial insulin resistance with acanthocythosis (spiky red blood cells) and acral hypertrophy: A rare syndrome characterised by enlarged hands and feet, velvety skin and muscle cramps;
  • Cancer-induced cramps; and
  • Natural muscle atrophy (muscle wasting): that occurs in people over 65 predisposes them to muscle cramps. 


Symptomatic muscle cramps

Symptomatic muscle cramps constitute the majority of muscle cramps and are related to underlying disease in a number of different body systems.

Muscle cramps are also associated with:


What causes muscle cramps?Muscle cramps

Muscle cramps are believed to originate from peripheral nerves (nerves outside the spinal cord) although the exact cause is unknown. These painful contractions may also be due to abnormal functioning of brain cells that control movement (motor nerves).

In some conditions the cause for the cramping will be evident; this includes endurance athletes, people over 65, people with underlying medical conditions or people on certain medications. That said, there are many situations where the cause of cramps will be undiagnosed. Further studies to differentiate muscle cramping are necessary to improve diagnosis and management.


What happens during a muscle cramp?

Muscles cramps range in intensity; some are relatively mild while others can be agonising. Cramps can reoccur multiple times in a single episode before they subside. In some instances cramps can be observed as visible distortion of the muscle and muscle twitching beneath the skin. The muscle may also be tense and hard when touched. Cramps can also vary substantially in duration from as short as a few seconds up to 15 minutes and in some cases even longer.


Diagnosis of muscle cramps

Doctors can usually distinguish muscle cramps from other muscle spasms after conducting a full medical history and physical exam. Your doctor may also ask several questions about the nature of your cramps to try to determine whether there is an underlying cause for your cramp. Important information about your cramps include:

  • Do the cramps occur after physical exercise of very mild intensity and duration? If so, does the cramping occur after every exercise session?
  • Does the cramping occur at rest?
  • Is the cramping associated with any other symptoms, such as pain, numbness, decreased sensation, or muscle weakness?
  • Is there anything that relieves the cramping? For example, does passive stretching relieve the contractions?
  • Is there a family history of cramping?


Treatment of muscle cramps


Non-pharmacological treatments

Muscle crampsNon-pharmacological treatments for cramps have no substantial evidence to support their efficacy however due to their ease, availability and nil risk, they should be used before pharmacological treatments are considered.

Exercise-induced cramping has been linked to dehydration and therefore rehydration is suggested to have a potential relieving effect.

Stretching three times a day has also been reported to reduce cramping in those who regularly experience cramping.

Muscle atrophy or muscle “wasting” occurs in the elderly as a result of decreased muscle use and therefore decreased muscle mass. Muscle atrophy can be combatted through muscle use through exercises, in particular resistance exercises. It follows that preventing muscle atrophy could also reduce the likelihood of experiencing muscle cramping.

Resistance training
For more information, see Resistance Training (Weight Training; Strength Training)


Pharmacological treatments

 

The pharmacological treatments that have shown potential efficacy in treating muscle cramps include:

  • Naftidrofuryl;
  • Diltiazem; and
  • Vitamin B complex.

Your doctor will advise whether pharmacological treatment is suitable for you.

 

More information

Fitness
For more information on fitness and exercise, including stretches, types of exercise, exercise recovery and exercise with health conditions, as well as some useful videos, see Fitness and Exercise.

References

  1. Katzberg HD, Khan AH, So YT. Assessment: symptomatic treatment for muscle cramps (an evidence-based review): report of the therapeutics and technology assessment subcommittee of the American Academy of Neurology. Neurology. 2010;74(8):691-6. [Abstract | Full text]
  2. Schwellnus MP, Drew N, Collins M. Muscle cramping in athletes – risk factors, clinical assessment, and management. Clin Sport Med. 2008;27(1):183-94. [Abstract]
  3. Hensley JG. Leg cramps and restless legs syndrome during pregnancy. J Midwifery Women Health. 2009;54(3):211-8. [Abstract]
  4. Elphick DA, Baker M, Baxter JP, et al. Muscle cramps are the commonest side effect of home parenteral nutrition. Clin Nutr. 2009;28(3):351-4. [Abstract]
  5. Serrao M, Rossi P, Cardinali P, et al. Gabapentin treatment for muscle cramps: An open-label trial. Clin Neuropharmacol. 2000;23(1):45-9. [Abstract]
  6. Miller TM, Layzer RB. Muscle cramps. Muscle Nerve. 2005;32(4):431-42. [Abstract]
  7. Muscle cramp [online]. Rosemont, IL: The American Academy of Orthopaedic Surgeons; May 2010 [cited 7 November 2010]. Available from: URL link


Drugs used in the treatment of muscle cramps

Diseases presenting with muscle cramps