why do muscles ache
Often, people who experience muscle aches can easily pinpoint the cause. This is because most instances of myalgia result from too much stress, tension, or physical activity. Some common causes include: 1  muscle tension in one or more areas of the body.ot all muscle aches are related to stress, tension, and physical activity. Some medical explanations for myalgia include: 1  fibromyalgia. 2  infections, such as the flu. 3  lupus. 4  use of certain medications or drugs, such as statins, ACE inhibitors, or cocaine.