there is such a thing as too much water.
Amazing it can show up in a marathon.
The Boston Marathon and Drinking Too Much Water
By JAMES DOWNIE
April 18, 2011
---------------------
...in the 2002 Boston Marathon, when a 28-year-old runner collapsed during the race and died two days afterwards from hyponatremia...
Three years later,
doctors from Harvard Medical School and Harvard School of Public Health reported in the New England Journal of Medicine on an analysis of runners in the same marathon.
After the race, [about 500 of the 766 participants] provided a blood sample and completed a questionnaire detailing their fluid consumption and urine output during the race." Disturbingly, "thirteen percent had hyponatremia (a serum sodium concentration of 135 mmol per liter or less); 0.6 percent had critical hyponatremia (120 mmol per liter or less)...
[T]he strongest single predictor of hyponatremia was considerable weight gain during the race, which correlated with excessive fluid intake."
The authors concluded, "hyponatremia occurs in a substantial fraction of nonelite marathon runners and can be severe."
-----------
https://newrepublic.com/article/86985/the-boston-marathon-and-drinking-too-much-water
Marathon Runners: Beware Of Drinking Too Much Water
January 11, 2008
Source: Methodist Hospital, Houston
----------
“During the marathon a good rule of thumb is to drink about one cup of fluid every 20 minutes,” Muntz said. “Drinking any more than that over the course of the race can get you into trouble.”
A recent study of runners in the 2002 Boston Marathon found that 13 percent of those who finished the race developed hyponatremia. The majority of these runners reported feeling “fine” after the race. However, if someone who feels “fine” continues to drink water because they believe the nausea and weakness they are feeling is due to dehydration, they could easily end up having a seizure and falling into a coma. [same study as above]
-------------------------
https://www.sciencedaily.com/releases/2008/01/080109195002.htm