[kenny1999]

i see that some articles state that water intoxication is unlikely in daily life unless running marathon. Here I would like to know how running marathon will result in a
higher risk of water intoxication? I don't think those runner has really drunk too
much, as I see from TV, most of them just drink a little bit and throw the paper cup
away, and they also sweat a lot! so, how come they will have a higher chance
to suffer from this rare disease ?

Thanks!

[enahs]

Water intoxication is caused by an in-balance in electrolytes. When you exercise A LOT for a LONG period of time, you sweat a lot losing a lot of your electrolytes. If you only drink water during this process, you are constantly flushing more electrolytes out without ever replenishing them. This assume it is fairly pure water, such as good quality bottled water. I suspect most tap water would have more then enough electrolytes in them.