page_title: Marathon
section_title: Hydration
hierarchical_section_title: Marathon / Health risks / Hydration
context_page_description: The marathon is a long-distance race with an official distance of 42.195 kilometres, usually run as a road race. The event was instituted in commemoration of the fabled run of the Greek soldier Pheidippides, a messenger from the Battle of Marathon to Athens, who reported the victory. The marathon can be completed by running or with a run/walk strategy. There are also wheelchair divisions.
  The marathon was one of the original modern Olympic events in 1896, though the distance did not become standardized until 1921. More than 800 marathons are held throughout the world each year, with the vast majority of competitors being recreational athletes, as larger marathons can have tens of thousands of participants.
context_section_description: Overconsumption is the most significant concern associated with water consumption during marathons. Drinking excessive amounts of fluid during a race can lead to dilution of sodium in the blood, a condition called exercise-associated hyponatremia, which may result in vomiting, seizures, coma and even death. Dr. Lewis G. Maharam, medical director for the New York City Marathon, stated in 2005: "There are no reported cases of dehydration causing death in the history of world running, but there are plenty of cases of people dying of hyponatremia."
  For example, Dr. Cynthia Lucero died at the age of 28 while participating in the 2002 Boston Marathon. It was Lucero's second marathon. At mile 22, Lucero complained of feeling "dehydrated and rubber-legged." She soon wobbled and collapsed to the ground, and was unconscious by the time the paramedics reached her. Lucero was admitted to Brigham and Women's Hospital and died two days later.
  Lucero's cause of death was determined to be hyponatremic encephalopathy, a condition that causes swelling of the brain due to an imbalance of sodium in the blood known as exercise-associated hyponatremia (EAH). While EAH is sometimes referred to as "water intoxication," Lucero drank large amounts of Gatorade during the race, demonstrating that runners who consume sodium-containing sports drinks in excess of thirst can still develop EAH. Because hyponatremia is caused by excessive water retention, and not just loss of sodium, consumption of sports drinks or salty foods may not prevent hyponatremia.
  Women are more prone to hyponatremia than men. A study in the New England Journal of Medicine found that 13% of runners completing the 2002 Boston Marathon had hyponatremia.
  Fluid intake should be adjusted individually as factors such as body weight, sex, climate, pace, fitness (VO₂ max), and sweat rate are just a few variables that change fluid requirements between people and races. The International Marathon Medical Directors Association (IMMDA) advises that runners drink a sports drink that includes carbohydrates and electrolytes instead of plain water and that runners should "drink to thirst" instead of feeling compelled to drink at every fluid station. Heat exposure leads to diminished thirst drive and thirst may not be a sufficient incentive to drink in many situations. The IMMDA and HSL Harpur Hill give recommendations to drink fluid in small volumes frequently at an approximate rate falling between 100–250 ml (3.4–8.5 US fl oz) every 15 minutes. A patient suffering hyponatremia can be given a small volume of a concentrated salt solution intravenously to raise sodium concentrations in the blood. Some runners weigh themselves before running and write the results on their bibs. If anything goes wrong, first aid workers can use the weight information to tell if the patient had consumed too much water.
caption: A volunteer hands out fluids at a marathon water stop
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