(HealthDay News) -- A muscle cramp is a painful contraction that may make the muscle feel hard or bulging.

The U.S. National Library of Medicine offers this list of common triggers:

• Drinking too much alcohol.
• Not drinking enough water.
• Exercising heavily or having muscles that are fatigued from overuse.
• Having hypothyroidism, a thyroid gland that doesn't produce enough of a certain hormone.
• Having kidney failure.
• Taking certain medications.
• Being pregnant.
• Consuming insufficient amounts of calcium or magnesium.

Related MedlinePlus Pages:

• Muscle Cramps