I think you have to think about how those people died. Heat exhaustion? An underlying heart condition? I don't think they died of not having enough nutrients, or not eating soon enough before running.
Sometimes stroke or similar, caused by incorrect hydration by just drinking lots of plain/plain-ish water which leave various useful things in your body too diluted to be useful. Sometimes an exacerbating factor in heat stroke, so not diagnosed as the heat stroke is seen as the only problem and other causes of heat stroke are assumed. See https://en.wikipedia.org/wiki/Water_intoxication
http://articles.chicagotribune.com/2011-06-04/news/ct-met-ha...
I'm just saying the whole "Push through the pain" adage is dangerous.