Fibromyalgia is a disorder characterized by persistent pain in muscles, ligaments, tendons, and joints. Additional symptoms of fibromyalgia, or FM, include fatigue, disturbed sleep and headaches, and these symptoms may be worsened or triggered by a host of factors, such as anxiety, depression, hormonal changes, cold or drafty environments, and/or stress. Physical overexertion is another possible trigger of FM, which the American Medical Association notes is the second most common disorder diagnosed by rheumatologists. The National Center on Health, Physical Activity & Disability notes that a healthy lifestyle that includes routine exercise, and aerobic exercise in particular, helps many people with FM more effectively manage their symptoms while preventing a decline in muscle strength, endurance and cardiovascular function. Exercise also improves oxygen delivery to muscles and reduces muscle tightness, each of which can eventually relieve some of the pain associated with FM. The rise in muscle temperatures during aerobic exercise may also alleviate symptoms of FM, as such a rise often makes it easier for muscles to relax.