Myalgia is a term for muscle aches and pains. Muscle pain also can involve ligaments, tendons, and fascia, the soft tissues that connect muscles, bones, and organs.
Myalgia is most frequently related to tension, overuse, or muscle injury from exercise or physically-demanding work. In these situations, the pain tends to involve specific muscles and starts during or just after the activity. It is usually obvious which activity is causing the pain.
Muscle pain also can be a sign of conditions affecting your whole body, like some infections (including the flu) and disorders that affect connective tissues throughout the body (such as lupus).