[_1100]

I remember my old track coach using this during practices.

We would swish the water around in our mouths to get rid of that bad taste you get when you’re thirsty, but he always warned us that the second we swallowed too much that practice was over because you get a stomach ache if you sprinted with all that water sloshing around.

[dalacv]

I have a theory that it isn't actually the water causing the ache, but rather the air that you drink while drinking the water. I've tried it and it works. See for youself: you have to drink a little bit differently (turn the water bottle upside down and be careful when drinking not to get air in. if you do, turn your head up and make sure you are only swallowing water.)

[why-el]

I think both you and the parent post are correct. I heard similar advice playing soccer: when you drink water during a game, what you usually do is drink it fast (and in a hand wavy way where the bottle is in the air). So the speed allows for more water and air, and thus you feel cramps. If you were to drink it slowly, which will reduce the air most likely, then you have less risk, but as a kid playing soccer, the urge to go back to the field is is too great. :)

[tharkun__]

Absolutely. This is worse when eating soup. You'd have to be veeeery careful when eating soup with a spoon. I always hated eating soups as a kid coz I'd feel so bloated after.