Fibromyalgia is a condition that affects between 3 and 10% of the worlds population, most of whom are female. It is most commonly found between the ages of 20 and 50. Also known as fibromyositis, Fibromyalgia is part of a group of common rheumatoid disorders (those not involving the joints). It is characterized by achy pain, tenderness, and stiffness of muscles. The painful condition of the muscles can occur as a result of stress, muscle injury, or muscle overuse. Tender areas in the muscles commonly called "knots" but in medical terminology called "tender points" create muscle spasm and tightness. Fibromyalgia is not contagious, and recent studies suggest that people with fibromyalgia may be genetically predisposed. It affects more women than men, with a ratio globally of 3-5:1.