Exercise intolerance
Fibromyalgia can cause exercise intolerance in the patients. Studies have shown that blood flow to the muscles during exercise is lower than normal in people suffering from this disease which leads to excessive accumulation of lactic acid in muscles. Excessive accumulation leads to muscle related pain in these patients.
In fibromyalgia patients, pain-blocking pathways are less active and less responsive which can restrict the release of endorphins. Hormonal factors may also play a role in causing intense pain and fatigue after exercise. For example, growth hormone can help repair muscle tears that occur after exercise. But studies have revealed deficiencies in growth hormone in these patients leading to defect in repair of those muscle tears. This can also cause intense muscle related pain and fatigue.