This is what I need to know:
I'm almost sure you can die of exhaustion, I just don't know how it works. I don't mean sleep deprivation, though I know that can definitely be fatal. What I mean is, something like the legend of the Runner of Marathon, who delivered news of a victorious battle and then dropped dead.
So, is it possible to push one's (normally healthy) body to the point where it just gives up and crashes? What would 'crash', so to speak? (Heart? Lungs? Deadly buildup of lactic acid? None of the above?) And can you be brought back from the brink at the point of collapse? If so, how? Glucose? Adrenaline? Enforced bed rest?
As usual, any help with this would be appreciated beyond measure. I literally can't continue until I know the answer to this. It'll affect the outcome of the whole story.
ETA: Thank you to those who responded. Obviously my post wasn't clear enough, however. I was more interested in how someone might be saved from dying from exhaustion, and what the symptoms might be, rather than if it was just possible (since I was almost certain it was). Since it seems that heart failure is the first and bigger threat, I'll go with that. Thank you again.