Due to continuous muscle use throughout long distance exercise events, they muscles generate excess heat as a byproduct of aerobic respiration, to prevent high temperatures the hypothalamus triggers thermoregulatory responses like sweating, although the body has combated the high temperatures, the cooled sweat evaporates and in doing so causes water and electrolyte loss, generating a need to rehydrate to replace loss fluids, if the fluids aren't replace the blood volume decreases which then reduces the oxygen and nutrient transport rate to organs and low blood volume decreases the blood pressure that impairs circulation and heat dissipation in the individual.