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Freebase(4.82 / 22 votes)Rate this definition: Muscle pain. Myalgia, or muscle pain, is a symptom of many diseases and disorders. The most common causes are the overuse or over-stretching of a muscle or group of muscles. Myalgia without a traumatic history is often due to viral infections.
What are muscle cramps? A muscle cramp is a strong, painful contraction or tightening of a muscle that comes on suddenly and lasts from a few seconds to several minutes. It often occurs in the legs. A muscle cramp is also called a charley horse. Nighttime leg cramps are usually sudden spasms, or tightening, of muscles in the calf. The muscle cramps can sometimes happen in the thigh or the foot.