Fibromyalgia's most common symptom could be a direct cause for exercise intolerance.
Because one of the most common symptoms of fibromyalgia is nerve and joint pain, it's entirely possible for it to be connected to exercise intolerance. This makes researchers believe that fibromyalgia might be a direct cause for the muscles to not get enough oxygen while the body is active. This connection has been made before in 1999 and 2003, providing researchers with a huge clue.
Hyperventilation is another issue that is related to the nerves. Those who are exercise intolerant often find themselves hyperventilating when they attempt to exercise. With this, the small nerves that control breathing might not be functioning properly to increase both the heart and breathing rate.