Dehydration

As little as 2 percent dehydration will have a negative effect on your race performance

Definition

Excessive loss of bodily fluids. Symptoms include thirst, dizziness, weakness and nausea. Serious dehydration can lead to cramps, chills and disorientation.

Remedies:
Stop running, get to a cool place and drink plenty of fluids.

Of course, the point is not to become dehydrated in the first place. Everyone's fluid needs vary. You know you're getting enough if you void large volumes of pale urine at least six times a day (note: B vitamins turn urine yellow-green).

To determine how much liquid to take during a run or race, you need to know your sweat rate, and that can vary between 1 and 4 quarts per hour. Weigh yourself nude before a timed training run, and then again after. One pound of weight loss equals 1 pint of water loss. Calculate your sweat rate and use this to determine your fluid needs during a run or race.

For example, if you lose 2 pounds during an hour run, that's 2 pints or 32 ounces. Thus, you need 8 ounces of water or sports beverage every 15 minutes. (Performance note: As little as 2 percent dehydration will have a negative effect on your race performance.)