Muscle Cramps

muscle cramp
Muscle Cramp. Jeannot Olivet/Getty Images

Muscle cramps (also called muscle spasms or charley horses) are are sudden, sustained, involuntary contractions of a muscle or group of muscles. The cramping muscle becomes tight and hard, and is invariably very painful. In fact, a muscle cramp is almost always painful enough to get you to stop doing whatever it is you were doing when it began.

Cramps can happen with any muscle, but most typically occur in the calf and foot muscles.

Other muscles commonly prone to cramping include the thigh, hamstrings, muscles of the arms and hands, and rib and abdominal muscles. 

Muscle cramps are a pretty common event. Almost everyone, sooner or later, will experience muscle cramping.

What Causes Muscle Cramps?

Electromyography (EMG) studies have shown that muscle cramps begin with increased activity in the nerves that supply the muscles, and not with the muscles themselves. It is now thought that muscle cramps represent a neural event and not a muscular event. 

But what causes the neural “twitches” that lead to a painful muscle contraction? The best we can do today is to list the various conditions that are often associated with muscle cramping. These include:

  • Idiopathic. The large majority of muscle cramps cannot be attributed to any identifiable cause. When doctors don’t know the cause of a medical phenomenon, they say it is “idiopathic,” which sounds more sophisticated than saying, “I don’t know.”
  • Biomechanical. Leg cramps can be associated with flat feet or other structural abnormalities of the legs and feet. Cramps are also more common in people who spend too much time sitting, or standing on concrete flooring.
  • Neurological. Several neurological conditions can increase muscle cramping, especially Parkinson’s disease.
  • Dehydration. Dehydration from diuretics or excessive sweating may lead to muscle cramps.
  • Electrolyte disorders. -Low blood levels of potassium, calcium or magnesium are associated with muscle cramping.
  • Pregnancy. Muscle cramps are more common during pregnancy, possibly due to magnesium depletion
  • Metabolic disorders. - Diabeteshypoglycemiaalcoholism, and thyroid disease are associated with muscle cramping.
  • Peripheral artery disease. Peripheral artery disease can cause leg cramping during exercise, when the exercising muscles are not receiving sufficient blood flow. 
  • Dialysis. People on dialysis are extremely prone to muscle cramping, particularly during treatment.
  • Nocturnal leg cramping. Nocturnal leg cramping — muscle cramps that occur while in bed (either awake or asleep), usually affecting the calf or foot muscles — are extremely common in any age group, although they appear even more commonly after the age of 50. Their chief medical significance is that they disturb sleep, and may produce sleep deprivation if they are persistent. 
  • Athletic activity. Prolonged or strenuous athletic activity, especially during hot, humid weather, can trigger muscle cramps. These are thought to be due to the dehydration and electrolyte disturbances that are common to this kind of activity. Acclimating to the heat, as well as staying well-hydrated (and sometimes, using electrolyte replacement) can help to prevent this type of muscle cramping.

Despite this long list of potential causes, in the large majority of cases muscle cramps have no particular cause — they are idiopathic.

How To Treat Muscle Cramps

When you experience an acute muscle cramp, you can generally relieve it rapidly by stretching and massaging the affected muscle. Icing the muscle or an Epsom salt bath might also be helpful. If the cramp occurred during strenuous or prolonged exercise, it’s time to take a rest and get rehydrated. However, if you experience leg cramps regularly while walking or climbing stairs, you may have peripheral artery disease. In this case you should definitely see your doctor for an evaluation.

If you have nocturnal leg cramps, regularly stretching your calf muscles may help prevent the episodes, as well as getting regular exercise. Wearing properly fitted shoes can also help. And loosening the bed covers at the foot of the bed (not tucking them in) can help prevent cramping.

If cramping is frequent or severe, or if nocturnal leg cramps are preventing sleep, you should consult with your doctor.

A Word From Verywell

Muscle cramps are quite common — almost everyone will have a cramp once in a while. Most of the time there is no identifiable cause, or the cause is transient. However, muscle cramping can also be associated with various medical conditions that may require attention. If you have muscle cramps that are recurrent or are otherwise particularly disturbing, you should have a medical evaluation. 

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Article Sources
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  • American Academy of Sleep Medicine. Sleep Related Leg Cramps. In: International Classification of Sleep Disorders, 3rd ed., American Academy of Sleep Medicine, Darien, IL 2014. p.299-303.
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