When discussing the topic of Cramps, we will break it down into two general heading - Muscle Cramps and Stomach Cramps. Stomach Cramps are sort of a misnomer, because the stomach is not really getting knotted up like a muscle, so we will actually look more at some of the causes and cures of common Gastorintestinal problems while training and racing. When a muscle has been working hard, or is over worked, it will sometimes involunarily knot-up or spasm. This is very painful and can easily bring the strongest athlete to his or her knees. Heat Cramps are caused by an imbalance of electrolytes in the bloodstream.
Electrolytes are positively or negatively charged elements necessary for muscle function.
A proper electolyte balance is necessary to keep muscles contracting normally. If the balance is off, the muscles may start to contract involuntarily, and that's a cramp. Fatigue Cramps would be less related to your electrolyte balance and more related to your muscles working hard and then sort of getting stuck in one position. For example, a foot or calf cramp during the swim leg of an Ironman is not due to an electrolyte imbalance, it would be caused by the muslces in the foot or calf contracting in one positon too long. Pointing the toes when you swim long distances may cause the muscles on the bottom of the foot to cramp.