(1) Death. The state of being dead. Deadness. Deathablement. Extended deathiness closely following any exercise, like breathing, for example, or just getting out of bed. (It happens.) Death can be brought on by many causes but the most common is dying.
(2) A side-effect of cotton clothing. You know how it is when you're huffing along and sweating all over, and basically generating clouds of steam because you're so stoked? And then you stop, and in a few minutes, because your clothes really are all wet, and you aren't generating those 1800 kilowatts of energy any more, you get cold, and then you almost croak from hypothermia? Well, that's post exercise chill. Either that or you really are dead, and that wasn't exercise you were doing, just some residual twitching. That happens too. Remain alert for the telltale signs.