If the brain's blood supply is decreased too much, the person may pass out (syncope). Symptoms may worsen when changing position from lying down or sitting, to standing up. In addition to feeling dizzy, associated symptoms may include: 1  Sweating. 2  Weakness. 3  Nausea and vomiting. 4  Shortness of breath. 5  Chest pain.
Although most muscle cramps are harmless, some may be related to an underlying medical condition, such as: 1  Inadequate blood supply. Narrowing of the arteries that deliver blood to your legs (arteriosclerosis of the extremities) can produce cramp-like pain in your legs and feet while you're exercising. 2  Nerve compression.
Unknown cause (idiopathic leg cramps) In most cases the cause is not known. One theory is that cramps occur when a muscle that is already in a shortened position is stimulated to contract. As the muscle is already shortened, to contract further may cause the muscle to go into spasm.