Muscle Cramps, Contractures, or Spasms

Cramp vs spasm vs contracture

Muscle cramps

A cramp starts in the nerve endings that control the muscle, which fire rapidly and uncontrollably. The muscle bunches into a visible, hard lump. Calves, feet and thighs are most often affected. The classic charley horse is a calf cramp. They are very common: most adults over 50 have night leg cramps at times. See muscle cramps.

Muscle spasms

"Spasm" is a broader term:

• Protective spasm: muscles tighten around an injury, such as back muscles after a strain. See muscle spasm.
• Twitches (fasciculations): small flickers under the skin, usually harmless and linked to caffeine, stress or fatigue.
• Spasticity: stiffness and jerking after damage to the brain or spinal cord, as in stroke, multiple sclerosis or cerebral palsy. See spasticity.
• Dystonia: sustained contractions that twist a body part, such as the neck or hand. See dystonia.
• Tetany: spasms of the hands and feet from low calcium or overbreathing.

Muscle contractures

The word has two medical meanings:

1. Physiological contracture: in some metabolic myopathies, such as McArdle disease (glycogen storage disease type V), muscles run out of energy during exercise and lock in a painful, shortened state. Unlike a cramp, the muscle is electrically silent on testing and stretching does not relieve it quickly. Dark urine may follow.
2. Fixed contracture: permanent shortening of muscles, tendons or joint tissue that limits movement. It follows immobility, burns, spasticity, cerebral palsy, muscular dystrophies and arthritis. See joint contracture.

Common causes of cramps and spasms

• Muscle fatigue and overuse, especially in unaccustomed or prolonged exercise
• Dehydration and salt loss from heavy sweating, especially in heat (heat cramps)
• Night cramps, more common with age, sitting for long periods and pointing the toes in bed
• Pregnancy, especially the second and third trimesters
• Medicines: diuretics, statins, some asthma inhalers (beta-agonists), raloxifene, some antipsychotics
• Electrolyte problems: low potassium (hypokalemia), magnesium, calcium or sodium

Medical conditions to consider

• Nerve conditions: peripheral neuropathy, pinched nerves, ALS (cramps with weakness and twitching)
• Kidney failure and dialysis
• Liver cirrhosis
• Thyroid disease: both underactive and overactive
• Diabetes
• Peripheral artery disease: calf pain when walking that stops with rest (claudication), not a true cramp
• Metabolic and inherited muscle diseases: cramps or contractures triggered by exercise, often from childhood

How doctors assess muscle cramps and spasms

A doctor will ask which muscles are affected, when the problems occur (rest, sleep, exercise), how long they last, your medicines, alcohol use and fluid intake, and look for weakness, wasting or twitching.

Tests depend on the clues:

• Blood tests: potassium, magnesium, calcium, sodium, kidney, liver and thyroid function, glucose and creatine kinase (CK, a marker of muscle damage)
• Urine test for myoglobin after an episode with dark urine
• Nerve conduction studies and EMG if a nerve disease is suspected. EMG also distinguishes a cramp (electrically active) from a metabolic contracture (silent)
• Exercise testing, genetic testing or muscle biopsy for suspected metabolic myopathy

What helps

Relieving a cramp now

1. Stretch the muscle. For a calf cramp, straighten the leg and pull your toes toward you, or stand and lean into a wall with the heel down.
2. Massage the knotted area.
3. Walk around or put weight on the leg.
4. Heat to relax the muscle, then ice if it is sore afterward.

Preventing cramps

• Stretch your calves and hamstrings for a few minutes before bed and before exercise.
• Stay hydrated, and replace salt during long exercise in heat.
• Avoid sitting with legs bent for long periods, and keep bedding loose over your feet.
• Ask your doctor whether any medicine could be contributing.
• Quinine is no longer recommended for leg cramps in the US because of serious side effects. Evidence for magnesium supplements is weak in non-pregnant adults.

Treating spasms and contractures

• Protective spasm: heat, gentle movement, pain relief and physical therapy
• Spasticity and dystonia: physical therapy, oral medicines, botulinum toxin injections
• Metabolic contractures: pacing exercise, warming up gently, and specific dietary strategies under specialist advice
• Fixed contractures: daily stretching, splints, serial casting and sometimes surgery to release tendons

Frequently asked questions

What is the difference between a cramp and a spasm?

A cramp is a specific type of spasm: a sudden, painful, sustained contraction that usually lasts seconds to minutes and is relieved by stretching. Spasm is a broader term covering twitches, protective tightening after injury, spasticity and other involuntary contractions.

What is a muscle contracture?

A contracture is a muscle that stays shortened. In rare metabolic muscle diseases, it is a painful temporary locking during exercise. More commonly it refers to permanent shortening of muscles and tendons that limits joint movement, from immobility, burns, spasticity or muscle disease.

What causes frequent muscle cramps?

Common causes include muscle fatigue, dehydration, aging, pregnancy, medicines such as diuretics and statins, and low potassium, magnesium or calcium. Kidney disease, thyroid problems, diabetes and nerve disorders can also cause frequent cramps, so recurrent cramps deserve a blood test.

Are muscle cramps a sign of something serious?

Occasional cramps are usually harmless. See a doctor if cramps are frequent or severe, affect many muscles, come with weakness, wasting or twitching, start after a new medicine, or are followed by dark urine. These can point to nerve, muscle or metabolic disease.

How do you stop a charley horse fast?

Stretch the muscle right away: straighten your leg and pull your toes toward your knee, or stand up and press your heel to the floor. Massage the knot and walk around. Most charley horses ease within a minute or two.