1 Service Details Priority Mail ExpressÂ® Overnight Guarantee1 Delivering 7 days a week, this is our fastest domestic service for time-sensitive letters, documents, or merchandise. 2  Guaranteed overnight scheduled delivery to most locations2, including PO Boxes, or your money back1. 3  From $13.09 online.
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.
Muscle tension is the feeling that muscles are always tight or strained, sometimes to the point of frequent pain, or even persistent and ongoing pain. One can experience tension, pain or cramps in any of the body's muscles as a result of muscle tension. The common symptoms of muscle tension are listed on the right.