There are three various stages of hyperthermia: heat cramps, heat exhaustion, and heat stroke.
Heat cramps are muscle spasms, or cramps, that are thought by some to result from the body losing too much salt during profuse sweating. The cramping is made worse when not enough salt is taken into the body.
Extreme physical exertion in a hot, humid environment can produce a disturbance of the body’s blood flow, resulting in a mild state of shock. This is brought on by the pooling of blood in the vessels just below the skin, which causes blood to flow away from the major organs of the body. Due to prolonged, profuse sweating, the body loses large quantities of salt and water.
If measures are not taken to remove the patient to a cool environment or to stop physical activity and replace lost fluid, conditions can deteriorate.